Time for wiring tips and tricks, got any?

[Tman]

Hey kids, getting ready to wire the Touring. I have a nice little panel. A sipmle HL switch, an ignotion switch, 2 head lights, tailights and tag light. No blinkers or any other goodies.

Talking to an old aircraft mechanic today, he said he has his headlights on separate circuit breakers so if one goes, you still have at least one headlight? Seems pretty smart, as I have been in Sodbusters sedan when the world went dark, couldnt even find my beer! http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

Any other tips and tricks from those that know more than me?

[Tman]

Here is the panel I am using $60 bucks retail, cant buy the parts separate for less.

[smittyshotrods]

Grounds! Don't rely on sockets and such to self ground. Run ground wires. My two cents!

[Hot Rod To Hell]

Don't mount your headlight relays in a spot that they'll get wet if you're stuck in the rain!

Don't ask how I know! http://www.jalopyjournal.com/ubbthreads/images/graemlins/blush.gif http://www.jalopyjournal.com/ubbthreads/images/graemlins/crazy.gif

[slazzen]

wow that thing looks fancy i used a $13 fuse panel and a ballast resistor grounded everything and soldered and shrink wrapd every connector took jeff about 4 hours to do the whole car

[Chuck Fish]

Use GM weather pak connectors under the car.They are waterproof and you'll enjoy life much more better when it rains.

Chuck Fish

[heyitsnate]

and another dude four minutes to undo the whole car!

[Tman]

WeatherPac stuff is cool. I read and re-read my parts house electrical picture book!

[WZ JUNK]

I am think of changing the wiring on the headlight circuit on my truck. I may wire in a relay on each headlight circuit to fire the lights instead of the power going through the switch. I have seen the difference it makes. I

[Slide]

I put a small dab of dielectric silicone grease on pretty much any terminals or connections. Keeps out corrosion and makes it easy to pull back apart when you need to!

If you have one of those aftermarket kits where all the wires are labeled, but you need to add some circuits or something, you can use leftover wires from elsewhere in the kit and wipe 'em down with lacquer thinner to remove the labels to avouid confusion.

Garbage bag twist-ties are a great way to temporarily hold wires in place till you get everything run. Then you can go back and tighten it up with tape or zip ties, whatever you prefer.

[dabond]

I like to lace my wiring with a waxed nylon lacing twine. That way, if a wire burns, it will melt the loom and not melt into the rest of the harness. Also taped harnesses are a bitch and look like hell.

[dixiedog]

Maybe a remote disconnect switch to disable the ignition.

[Roothawg]

[ QUOTE ]
I am think of changing the wiring on the headlight circuit on my truck. I may wire in a relay on each headlight circuit to fire the lights instead of the power going through the switch. I have seen the difference it makes. I

[/ QUOTE ]

Explain your self young man......

[LIMEY]

I always crimp, solder, & heat shrink, also use heat proof sleeve where its needed & grommets where the wiring passes through a panel.
Nothing worse than chasing bad wiring at the side of the road, take your time it will pay off.

[theodore]

Route your wires before cutting and hooking up headlites and what not, the six inch extensions on every circuit look ugly. I used an old honda fuse panel, works killer, just hooked the headlites up with a breaker and haven't had a problem yet.

[just steve]

While we're talking wiring . . . I've seen modern plastic-insulated wiring that's wrapped in the old-style braided-cloth covering for restoration work.

Anybody got a source for that kind of wiring in bulk? Lots of places sell harnesses made with it, but haven't seen it in bulk.

I want the '32's harness to look "right."

Steve.

[Tman]

Steve, I forget the company, look in FARM COLLECTOR Magazine, there is usually an advertiser that sells to the tractor restorers.

[KATFISH]

Try "YNZ Yesterday's Part's For this type of wire
Phone (909) 798-1498

[The37Kid]

KILL SWITCH!!!!!!!!! Electrical work scares me, it can turn your car into toast and the garage and house with it.

[Bruce Lancaster]

Anybody got a source for that kind of wiring in bulk? Lots of places sell harnesses made with it, but haven't seen it in

Brillman's, Sacramento.
Sacramento has I think all the basics you need to do Ford color code.

[Bruce Lancaster]

Also, on grounds, build a ground wire for each head/tail light, gen, reg, instrument cluster right into the harness as you make it so all is neat. Get everything important grounde so body/frame/bat ground are all tied together by wire and cable and all major units are tied in. Normal everything-bolted-together ground is no good in a rebuilt car because your painting of mechanical parts will be much thicker than factory dip. Use lotsa star washers and dielectric grease. I like oversize wire on major circuits, too.

[4gotn1]

Run a couple of extra wires in your loom when you're running everything through. They make for quick repairs if you burn one wire up and also make it handy if you decide to run some sort of accessory later.

[banzaitoyota]

http://www.rotaryinnovation.com/new_products[1].htm


Self fusing silicone wrap that is heat resistant to 500ºF works good.

Use REAL crimpers not the $3.00 set your dad bought at JC Whitney

[whodaky]

Ditto on the Kill switch, it saved my coupe from becoming a fireball!!! Geoff aka Whodaky

[BenD]

Kill switch, hidden aux outlet, and fuel pump toggle if using and electric pump.

[RileyRacing]

IDK if they still do, but you could buy that cloth wrapped modern type wire from AC/Delco distributors, at least as recently as 5 yrs ago... it comes in 50/100 ft lengths.

Jay

[Tman]

Keep those tips coming, I posted this more for others than myself really.

As for the cloth wrapped wire, CARQUEST list different sized cloth loom in their Electrical Catalog. You just slide your modern wire in it.

[speedaddict]

Drop the car off with me and pick up my 39, we'll do some trade work http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[Tman]

Speed, that actually would be kinda fun, up to the point where I like to do as much as I can myself! http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[cosmo]

Relaying the headlights is a brilliant idea (literally!!), you can go further and relay each beam on each lamp, might be overkill, but it'll work killer and you'll only ever lose one beam of one lamp if there's a problem.
Mercedes (and others) fuse each beam of each headlamp (no relays).
Loud horns. Get Fiamm brand, or grab 'em out of a Tempo/Topaz (right front inner fender, behind headlamp). These are the loudest stock horns I have heard.
Solder. And learn to solder correctly. I use liquid flux on every joint, along with heatshrink and a GOOD set of crimpers. A good solder joint is shiny.
Grease all connections everywhere. And dielectric grease is not strictly necessary, wheel bearing grease will work fine, too. But don't use lithium...it conducts.
Use the colour codes from a factory, any factory (I use mid-sixties GM codes for older cars). It'll make your life a little easier choosing colours and such. Write down what you do in any case.
Don't use the plastic-sleeved connectors, or at least take the sleeves off. Heat-shrink is much better/neater.
Have EVERYTHING mounted where it will be when you start wiring. Makes a neater job by far.
Run wires over the doors, never under carpet. Under the sill plates if it's a convertible.
Feed the third brake light from the brake light switch, BEFORE the turn signal switch. Flashing third brake lights make me think - MORON.
More interior lights rather than fewer. My last rod had 9 interior lights. I could find things I dropped in the night. And it looked comfy when getting in at night.
You must run either a fusible link or a main-type fuse (60-80 amp) from the starter (maybe more than one). This will blow if things get ugly close to the power source (starter solenoid).
Never run starter power through a kill switch. It can't hold up to the power; wasn't designed to either. Safer to run all the vehicle power through a kill switch, after the fusible link (s).
Look at and follow loosely a factory wiring diagram to determine circuits needed. Frequently the factory run two or three fusible links, effectively dividing the power so you don't loose the whole car (power) at once.
Keep it simple. Every connection is an invite for corrosion/trouble. Fewer connections equal more potential reliability. And less voltage drop.
Cosmo

[Fat Hack]

Most points have already been covered, but here's some tips I followed when wiring my 49 Chev in a similar fashion to what you're doing (basic lights and engine wiring, plus fan and fuel pump...no blinkers or reverse lights)...

1. WIRE ONE COMPONENT AT A TIME! For my car, I used the fusebox (aftermarket job that holds the blade type fuses) as the central point in wiring each component. One end of a given fuse goes to the component, while the other end handles current input, either directly or from a switch.

By wiring up one component at a time and building your harness on the car as you go, you avoid confusion...and it makes testing each newly wired component a breeze!

2. WIRE IT LIKE IT'S A FIBERGLASS CAR! By that, I mean run ground wires to EVERY light and component. As already mentioned, don't rely on the body or the component for a good ground. Many electrical glitches are caused by bad grounds...avoid that problem by running dedicated ground wires to everything!

3. WHERE TO GROUND STUFF? My trick for wiring a car is to hook the negative battery cable to the engine block, then run a heavy Ford type switch-to-starter battery cable (eyelet on both ends) from the block to a bulkhead on the body...usually on the firewall. The ground wires from individual components also terminate at the same bulkhead, providing a solid, reliable ground. This is admittedly overkill, but a hefty 4ga ground strap means no grounding issues down the road!

Under the hood, I will run a ground wire from things like the headlights and electric fan back to the negative battery cable from a smaller bulkhead...no need to run the grounds for these things back inside the car if the battery is right there!

4. HEADLIGHT RELAYS! Yes, as people have already stated, using relays for your headlights is an excellent idea! I don't use one relay for each lamp, though...I use one relay for low beam and one relay for high beam, so that if one relay fails, you still have a back-up plan that gives you TWO working headlights.

5. COMPONENT/SWITCH LOCATION! Take a few minutes to think about how and where you are mounting things. For example, I put my dimmer switch up on the dash to keep it out of water and dirt on the rusty old floor. Keeping your electrical components and switches clean and dry is essential for obvious reasons...just think about it when you decide where things will go!

6. GREASING CONNECTIONS! I use a compound called No-Ox-Id that looks and feels sorta like chassis grease, but it provides a weather resistant seal and helps keep current flowing freely. I add it to each connection to eliminate any worry about corrosion on down the road! Other brands and variations are available. Don't be cheap...buy some and use it!

7. KEEPING WIRES OUTTA TROUBLE! Here's where I REALLY go overboard! I use rubber hose in various sizes to protect all my wires where they come into contact with anything metal. Never rely soley on the wire's insulation to protect the conductive part inside from becoming exposed due to rubbing and vibration...always use grommets, shrink wrap, electrical tape and even hose lengths to insure that your wiring harness outlives the car it's on! ANYWHERE a wire rest on or passes through metal (like the firewall), it NEEDS to have an extra measure of insulation around it.

Those are just some basic 'rules' I follow when wiring a car...some may seem overkill or too extreme, but I like the peace of mind that comes along with knowing that my electrical components are safely wired and will work as designed for a long time! A little extra time, thought and money spent on your wiring will save you countless headaches and hassles later!

http://www.jalopyjournal.com/ubbthreads/images/graemlins/cool.gif

[Django]

Does anyone have a source for GM color codes?

[Gr8ballsofir]

DON'T use cheap crimpers!! Klein Tools makes a decent set.

[rusty1]

Here is the panel I am using $60 bucks retail, cant buy the parts separate for less. Where did you get your fuse panel?

[Tman]

Where did you get your fuse panel?

That is a panel that I sell from PARR Automotive.

[SamIyam]

I've wired several cars with Painless kits... and I usually have to cut the wire ties off them so I do not have a lot of wires doubling back.

Map out all your lights, switches and stuff on your living room floor. Then lay the box there and run the wires where they need to go. Use electrical tape to temporarily tape the wads of wires together.... because as wires go around corners and make bends... the wires on the inside of the bends will be shorter, outside ones longer... so you'll have to re-tape or wire tie.

Mount box.

Then run looms where they need to go.... think of the routes your wires take as city streets... and don't cut across old man Harpor's yard to run a wire to the headlight switch...

When you terminate ends... take your basic plastic insulated connectors, and pull the plastic connectors off... I found some that come already plain in my dad's electrical pile... he was an electrician... anyway, you can make your own.

Then cut several pieces of shrink tube for your wires... do them all at the same time, so they all end up the same length. Avoid the cheap Radio-Shack shrink tube... buy your stuff at an electrical supply store. (you knew that already, 'cause you're a sharp cookie). I take and draw two parralell lines on my wood topped work bench with a ball point pen... and then use a razor blade to cut them all the same length...

Then slide the shrink tube onto the wire... cut your insulation back on the wire, slip the connector on... crimp it (try to find the ones that can crimp on the wire and the insulation) and then heat the heat shrink on...

I'll try to post some pics of this later tonight if I have time...

Sam.

[nero]

Anybody got a source for that kind of wiring in bulk? Lots of places sell harnesses made with it, but haven't seen it in

Brillman's, Sacramento.
Sacramento has I think all the basics you need to do Ford color code.
I AGREE WITH 32LIMEY CRIMP AND SOLDER,USE SHRINK TUBE.

[snapper]

All great idea's.


..........Mount that Halon extinguisher then wire car....H

[Leadsled51]

[QUOTE=just steve]While we're talking wiring . . . I've seen modern plastic-insulated wiring that's wrapped in the old-style braided-cloth covering for restoration work.

Anybody got a source for that kind of wiring in bulk? Lots of places sell harnesses made with it, but haven't seen it in bulk.

Just got Streamline's new catalog, it has some in it.

[HotRodChassis]

Think about how Detroit does it. They make a master body harness, then a harness for each major components (motor, front end (lights, etc.), out back). I've seen more rods that were hard to work on because there was just ONE BIG harness. Now way to remove or unplug if needs be. Also, you can get a 21 connector weather pack bulkhead plug and socket. Keeps the weather out around where the harness must pass from interior to exterior

[Digger_Dave]

... Use lotsa star washers and dielectric grease.

Like Bruce, I always used STAR WASHERS (they have teeth on them to "dig" into the connection) on every mechanical wire joint I made, until this piece "passed over" my desk.

Heck! I always used star washers on grounds!

This is part of a recent GM service bulletin......

This information applies to 1996-2005 passenger cars, trucks and utilities.
(but would apply to any newly rewired vehicle)

In the past, star washers have been used under most ground connections.
It was believed using a star washer would improve continuity to ground and prevent the ground fastener from becoming loose.

GM Engineering has determined that installing a star washer increases the chance for corrosion and prevents the terminal from achieving proper torque.

On vehicles being built today, star washers are NOT being used under any ground connections.

It is recommend NOT to use a star washer on any ground connection to the body or chassis of the vehicle.

TIP: Be sure the fastener and terminal are clean and corrosion free. When removing corrosion, be careful not to remove the plating from the terminal. Use dielectric grease between the connection and the ground point.

Also be sure to torque the fastener to the proper specification.

I guess you CAN teach an "old dog, new tricks!" (anyone need a supply of un-needed star washers?? )

[Dirty Dug]

I'm in the process of wiring my '32 coupe chassis. Two additional questions: does anyone know a good sourse for info on fuse sizes for each individual circuit like headlights, heater, horn, etc? Also, I've not heard of a relay for lights, what's that all about. I'm setting up my chassis like Henry did with all my electrical running to the dash tunnel so I'll be able to start the chassis before I mount the body. Any good advise for this application is also welcome. Thanks dug

[Django]

No one knows the GM color codes? I'm trying to build my harness from scratch.

[Foul]

Also, I've not heard of a relay for lights, what's that all about.

headlamp relay modification - http://www.danielsternlighting.com/tech/tech.html

I spent about $30 in wiring, connectors and relays doing mine. Not difficult at all to do or understand.
d

[atch]

as for soldering; years ago i bought a "pencil tip" soldering gun that uses a bic lighter and puts out a small sharp pointed flame. has anyone used one to wire a car with? that's what i bought it for but have lost it since then without ever wiring a car (i hate electric soldering guns). but i'll get another one if the consensus is that they work good. i need to do some rewiring on clarence. (right, jim c?)

sam - i like what you're saying; have you ever soldered in addition to crimping? opinion?

[Boones]

First, I envy all of you that can wire a car from scratch. I am a kit person, as electrical scares me..(hated electrical engineering class) as I can not see it, only feel it.

Can someone better explain the headlight relay, where you put the relay, how it is wired in.. I lack this knowledge but would like to know more to get better educated, so maybe one day I feel confident enough to tackle a job from scratch..

[Digger_Dave]

as for soldering; years ago i bought a "pencil tip" soldering gun that uses a bic lighter and puts out a small sharp pointed flame. has anyone used one to wire a car with? that's what i bought it for but have lost it since then without ever wiring a car (i hate electric soldering guns). but i'll get another one if the consensus is that they work good. i need to do some rewiring on clarence. (right, jim c?)

sam - i like what you're saying; have you ever soldered in addition to crimping? opinion?

atch, the Bic "Torch" will work for smaller connections.

I usually "tin" (flow a small amount of solder) on the ends of the wires after I have twisted them tightly.

Slide on the shrink tube.

Then crimp ** the wire in a terminal end. (non - insulated type)

Then I put heat on the terminal end just where the wire "peeks" out the inside of the terminal; and apply a small amount of solder, (ROSIN CORE ONLY!) until it "wicks" into the terminal end. Don't apply TOO much solder, or it will continue wicking past the terminal end and on into the wire itself. This will insure a good mechanical and electrical joint.

Once the connection has cooled, slide the shrink up UNTIL IT COVERS THE END OF THE WIRE THAT PEEKS OUT OF THE TERMINAL (inner end) I actually push extra up against the terminal. It will pull back when the shrink tube shrinks. This way the solder joint will be totally covered as well as the outer end of the terminal.

Then using a heat gun (or a hair drier) contine applying heat (rotate the wire to get an even shrink) until the shrink tube is tight all the way around.

** Even if your only going to wire ONE car; invest in a GOOD SET OF CRIMPERS!

AMP, KLIEN or any kind that have FORGED crimp indentations. Leave the stamped cheapies on the $1.00 table; waste of money.

[jusjunk]

Hey kids, getting ready to wire the Touring. I have a nice little panel. A sipmle HL switch, an ignotion switch, 2 head lights, tailights and tag light. No blinkers or any other goodies.

Talking to an old aircraft mechanic today, he said he has his headlights on separate circuit breakers so if one goes, you still have at least one headlight? Seems pretty smart, as I have been in Sodbusters sedan when the world went dark, couldnt even find my beer! http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

Any other tips and tricks from those that know more than me?

Ive done 5 cars then I decided to get a kit... No biggie I just soldered all the connections and heat shrinked em. I also use spade connectors on anything that may be removed later and use good scotch (3m) electrical tape to cover em from the elements. I used to make my own fuse panels with the glass fuses and everything and never had any trouble cept the time i hurried on my 30 sedan and forgot a grommet and the new buyer drove up to the micro brewery about a 1/2 mile and a wire rubbed thru and fried the alt wire:) Shit I had my money.. Actually it was no big deal and the car drove to the east coast.
Dave:eek:
Oh ya get a after market headlight switch with a breaker .....fuse everything good...............I even had a ford alt and regulator on a sb chevy once and they asked me how i did it...Used a motors manual :)

[desoto]

While we're talking wiring . . . I've seen modern plastic-insulated wiring that's wrapped in the old-style braided-cloth covering for restoration work.

Anybody got a source for that kind of wiring in bulk? Lots of places sell harnesses made with it, but haven't seen it in bulk.

I want the '32's harness to look "right."

Steve.

These guys http://www.riwire.com/ have every color combination imaginable.

I buy all of my lacquered cotton covered wire from them.

[desoto]

Like Bruce, I always used STAR WASHERS (they have teeth on them to "dig" into the connection) on every mechanical wire joint I made, until this piece "passed over" my desk.

Heck! I always used star washers on grounds!

This is part of a recent GM service bulletin......

This information applies to 1996-2005 passenger cars, trucks and utilities.
(but would apply to any newly rewired vehicle)

In the past, star washers have been used under most ground connections.
It was believed using a star washer would improve continuity to ground and prevent the ground fastener from becoming loose.

GM Engineering has determined that installing a star washer increases the chance for corrosion and prevents the terminal from achieving proper torque.

On vehicles being built today, star washers are NOT being used under any ground connections.

It is recommend NOT to use a star washer on any ground connection to the body or chassis of the vehicle.

TIP: Be sure the fastener and terminal are clean and corrosion free. When removing corrosion, be careful not to remove the plating from the terminal. Use dielectric grease between the connection and the ground point.

Also be sure to torque the fastener to the proper specification.

I guess you CAN teach an "old dog, new tricks!" (anyone need a supply of un-needed star washers?? )


The ground terminals on new cars have a ribbed pattern on both sides.

FWIW, I'm still seeing ribbed terminals and star washers on the relatively new cars I'm disassembling in the shop on a daily basis. Winter weather is great for my current line of business -- collision repair.

[WZ JUNK]

Joining two pieces of wire together with solder is always a challenge. I have tried different approaches but here is the way I do it now. I cut about a 4 inch piece of scrap wire and strip back the insulation all but about the last inch or so. That keeps the strands together. I pull out of this bundle one strand of wire. I use this single strand to wrap the area of the two wires together than I intend to solder. This holds the two wires together while I solder. Seems like any other method I tried, the wires would separate or move just as I was ready to solder.

[rev616]

No one knows the GM color codes? I'm trying to build my harness from scratch.

i dont know the codes,but maybe this could help you somehow?

http://www.tocmp.com/manuals/wiring/index.html (old car manual project,car wiring diagrams)

[rev616]

in my electrical classes at MMI,they always taught us,that when we splice connections or put on spade connects,or anything that needs crimping to solder them,and then crimp,then heatshrink.


also to join to wires together,we always cut about an inch of insulation off each wire,then we braided the wires around each other,so you couldnt pull them apart,and then soldered them,works great and it hard to pull apart even without solder

[Tman]

Joining two pieces of wire together with solder is always a challenge. I have tried different approaches but here is the way I do it now. I cut about a 4 inch piece of scrap wire and strip back the insulation all but about the last inch or so. That keeps the strands together. I pull out of this bundle one strand of wire. I use this single strand to wrap the area of the two wires together than I intend to solder. This holds the two wires together while I solder. Seems like any other method I tried, the wires would separate or move just as I was ready to solder.

Well, it is a surprise to see an old forgotten post resurface. After this post, I finished up my wiring on the Touring.

One of the things I did was to solder all my connections, even the terminals.
I have always liked shrink tube, so I used a bunch of that.

I used a bunch of self adhesive wire holders, the kind you run a zip tie through to hold a wire or wires.

All in all, it came out pretty good.

[WZ JUNK]

Well I do not know what to think about the star washer deal. I would say that I would still use them. I am kind of set in my ways. I mean they have worked for all these years, why change now. My only thoughts on not using them would be where you have a computer controlled or electronic device that is voltage sensitive. Maybe that little bit of corrosion would make a difference. Just when you think you are doing everything right , someone changes the rules.

[Automotive Stud]

here's a few more tips that I've used:

I used two small fuse panels from napa. They each hold 6 blade type fuses. I have one wired to constant power and the other wired to power with the key on for accessories.

For the headlights, I used a circuit breaker with blade terminals on the back that plugs into the fuse panel in place of a fuse. I used a 25 amp breaker. I used a universal napa headlight switch (with no dash dimmer or crap) that holds a 30 amp fuse, just in case the breaker dosn't catch something.

I have a pull switch for an electric fuel pump, in addition to my stock one.

Horns, use a relay.

I like to run wires for the same things together, like all the turn signal wires, bundled together with zip ties every 6 inches or so. After you have several bundles like this running near each other, tie them together every foot or so. Preferably a different color so you can easily tell which ties to snip to access on circuit. It makes it neat and easy to troubleshoot if needed.

I used a fancy label maker that was a gift to make neat little labels for all the wires, plus color codes that I made up as I went along and wrote down. I also used it to label each fuse on the panels, and label when each panel was hot.

All the wires under the car I used plastic loom to protect.

Disconnects are a good thing to put where needed. I like to have them on the lights outside the car, so if a parking or taillight assembly has to come out, you can disconnect it.

I also like to use shrink tubing on all connectors.

Be sure to leave plenty of slack, makes troubleshooting that much easier.

I liked the book "how to wire your streetrod" for lots of helpful info if your not buying a kit.

I did my '47 like this. I don't have too many accessories, but I did put in a hidden radio with 3 speakers, courtesy lights under the dash, a trunk light that comes on with the lid, and all the basic stuff, plus lighting for gauges under the dash. Nothing much, but I have more than enough circuits.

[burger]

Everyone seems to bash on the idea of using the body and/or frame as a common ground. The usual problem is that connections are made through painted or otherwise insulated surfaces. Here's a trick that gets around that. Weld 1/4 or 3/8 bolts to your chassis, firewall, the back of your dashboard, etc and use them for a solid ground connection. If you're planning to use the chassis/body as a common ground, run a heavy wire between the block and your chassis/body. It also helps to run a wire between the body and the chassis.


Ed

PS- Check out www.madelectical.com (http://www.madelectical.com) for more ideas.

[rich^vic]

Always use a fusible main link (55-60Amps). from the battery to the main circuit. 10ga or higher for main wires through the firewall. 4ga or higher for the starter (shouldn't exceed about 2-3 feet in length.. the longer the length, the higher the gauge you'll need to deal with internal resistance at starting time).
If you're using an electrical cutoff switch (kills all power) put it between the negative terminal of the battery and the frame and use the highest possible guage wire and the shortest possible run to connect it (the generator/alternator does not necessarily need to be isolated since it cannot generate the power of your battery at low rpm and has a much higer internal resistance).
Intrumentation wires should be 16ga or higher depending on loading and all connections should be soldered and coated with heatshrink to minimize short circuits.
Make a schematic and label all wiring colors. if you don't understand how a certain switch works either use a meter to figure it out, or consult a haynes or owners manual.
Electrical components outside the cab should be mounted to the firewall or driver's side wing and waterproofed.
You can choose any fuse box you like, but consult your schematic to guarantee that it has enough circuits to service the car. ALL power ciruits must be terminated at the fuse box or else you may have a fire if one fails.
All wires runs should be covered when passing through sheet metal or any abrasion area. flexible wire loom makes wires easy to service later on and usually looks discrete. if you're looking for fabric coating, you'll have to make sure that it is fire resistant.
It's good practice to use factory connectors where possible even if you do not use all of the functionality. If you need a new steering column you or the person who bought your car won't need to spend lots of hours figuring out custom wiring for a common part.
Where possible, keep all wiring to the front and rear sectors of the car as high up from the road as possible and if it absolutely must be exposed to the road, mount it on the side of a rail using any permanent fastener. generally avoid using zip ties, with enough vibration and weather exposure, they'll cut right through wires or come apart and drop the harness. the best way to secure wires it to use either the factory mounting flaps (little metal tabs that are welded to the fram and flex over the wires) or screw down, rubber insulated mounting brackets.
You may want to just buy a new harness, because making them is a pain in the ass. especially finiding the colors and connectorizing them.. you may have to modify a replacement harness, but a few modifications beats tracking down a used steering column connector or a firewall connector.

-Richard

[CharlieLed]

First, I envy all of you that can wire a car from scratch. I am a kit person, as electrical scares me..(hated electrical engineering class) as I can not see it, only feel it.

Can someone better explain the headlight relay, where you put the relay, how it is wired in.. I lack this knowledge but would like to know more to get better educated, so maybe one day I feel confident enough to tackle a job from scratch..
The function of a relay is to control a high current line using a low current control. In simple terms this means that you don't want to run all the current through the switch that turns your lights on and off...the switch would be HUGE. When using a relay the only current required at the switch is that which is needed to actuate a small electromechanical reed switch inside the relay. In other words, the current through the switch is very small...the high current going to the lights now runs through the contacts inside the relay.
The best example of a relay is the solenoid on your starter...could you imagine the size of your ignition switch if all the current that turned your starter ran throuch the switch instead of the solenoid?

[CharlieLed]

First of all I am not a big fan of complex color codes, GM or otherwise. If you have a cable running to a component in your car what are the chances that there are going to be more than a handful of seperate wires in that bundle? Red is always hot and Black is always ground...the rest is up to you. You are not building a hotrod for production that has to be serviced across the globe, do what's reasonable for you and then DOCUMENT it in detail.
I have seen some of the prefabricated wiring harnesses and, while they are good for the average car, I am not impressed by the quality of the wire...I should say, by the quality of the insulation on the wire.
If you can find teflon insulated wire then use it. It won't chafe and it won't melt...either through the process of soldering or by external heat from engines etc. I have a 94 Jeep that I bought new and now have over 161 K miles on...the valve covers have never been off of it but I have had three failures in the wiring under the hood related to insulation becoming brittle and causing the wire to fail.

[choprods]

I'll add a little tip for the cheapskates in this crowd!
Hope I didnt post same thing last year when this was new.......;)
A good way to wire Lights on a simple hot rod with few accessories ,is to do this......
Go to the Farm store or Wal Mart and buy one of those TRAILER wiring kits -usually from 9.99 to 28 dollars depending on whether they include taillights ot just the wire.....
It usually comes with a FLAT 4 wire tape style wire loom and can even be had in a 6 wire of this flat style.
These are color coded to match taillights on the towing vehicle.
I suggest running this frt to rear[think they are 26-30 ft long] and then allow enough length to reach the turn signal switch on column.
this will be enough wire to do all the rear and all the front[turn -park] light circuits. also it would be seperated at the stop light switch so that way they will work seperately from the park/turns on the front.......
also the taillights are nice to mount UNDER the rear of a T or A when you are using those DIM 48 chevy or 39 ford taillights that dont show up well at night.
Just mount them UNDERNEATH to the trunk floor facing DOWN:) - and at night they will REALLY light up the rear and highway and can be seen as well as a late model!

[desoto]

If you're using an electrical cutoff switch (kills all power) put it between the negative terminal of the battery and the frame and use the highest possible guage wire and the shortest possible run to connect it (the generator/alternator does not necessarily need to be isolated since it cannot generate the power of your battery at low rpm and has a much higer internal resistance). -Richard

That's not a good idea, especially if you have a radio or engine management computer that requires constant voltage.

If you put the kill switch in the negative battery cable you still have to run the ECM and radio grounds (earths, for you Aussies) back to the battery.

In doing so, you've just bypassed the kill switch with the internal circuitry of your radio and ECM and those wires aren’t anywhere sufficient to carry the load of the starter motor which WILL operate when you turn the key regardless of the position of your kill switch.

The whole idea of installing the kill switches in the negative lead stems from their original application i.e. positive ground/earth construction equipment. With positive ground, you're installing the kill switch in the “live” wire when you put it on the negative side .

Install your kill switch in the live cable and as close to the battery as possible.

[Levis Classic]

GREAT POST and very timely for me.

[rat bastad]

This post is one of the BEST tech posts Ive seen on the HAMB, full of great tips and do's and dont's. Esp since Im 3/4 of the way through wiring my Deuce and believe me, I hated wiring but Im quite happy with how this is turning out. Simply put, Im a cheep bastard and cant afford to pay a sparkie for his time where I could use the money to go into my 4-71 blower.

Im using am EZ wiring harness....so far so good. Im also going overkill on the grounding of the car (block to chassis, batt to chassis, chassis to body front and rear and each component individually grounded to clean, fresh unpainted metal. Most of my connections have been crimped with a proper crimper, soldered and heat shrunk too.

I have the starter solenoid/fuel pump and brake lite switch under the floor and am wondering if I should use die electric grease to keep corrosion off the connections that are exposed to the weather?? Do you just put the stuff on the connections and thats it? How does this stuff work?

Some things I learned? Well....

i. Always leave enough wire to allow for bends etc....
ii. Only take on one section at a time till its completed PROPERLY.
iii. You can label wires with written masking tape attached to the wire to
identify each wire down the track if required.
iv. Take your time and try to make it as sano as possible.
v. Use the proper tools and materials
vi. Study up to learn a little about what you are doing
vii. Use male/female plugs so that you can remove components easily down
the track ie: dash or gauges.
viii.Ground everything properly esp on a glass car.
ix. Plan where youre gonna run the wires...try and hid'em for a sano job.
x. Carry a fire extiguisher (In case I screwed up lol)!

Anyway...thats what Ive picked up wiring my ride from scratch....I just ihope it all works ok. I couldnt bear chasin down shit to find out where its went wrong.

Rat

[injectedA]

Haven't time to read all this yet, but some good stuff. Not much to add, just a small tip. When running wire in an area where it can be caught/snagged by a sleeve/tool or other like at the coil on the firewall or the rear of the alternator, I leave like 6" extra, and wrap this tightly around a long socket to match the wire. Like a 3/8" round for 12-16, or a 3/4" for 8-10. Now when yanked on it stretches. Plus it looks kinda trick. and heat shrink heat shrink heat shrink...

[Imwalkin]

For those who use crimp on connectors. When crimping put the dimple from the crimping tool on the side of the connector with out the split. When you crimp the split side the split can fold and the wire can easily pull out.. And what everybody else said use good crimpers.

[banzaitoyota]

DO NOT USE ELECTRICAL TAPE!! The adhesive oozes everywhere. This stuff is pretty nice for wrapping harnesses


http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7957376412&rd=1&sspagename=STRK%3AMESE%3AIT

[tommy]

Haven't time to read all this yet, but some good stuff. Not much to add, just a small tip. When running wire in an area where it can be caught/snagged by a sleeve/tool or other like at the coil on the firewall or the rear of the alternator, I leave like 6" extra, and wrap this tightly around a long socket to match the wire. Like a 3/8" round for 12-16, or a 3/4" for 8-10. Now when yanked on it stretches. Plus it looks kinda trick. and heat shrink heat shrink heat shrink...

I seem to wire alot of highboys with removable lights. I like to use the old Ford "bullet" connectors. (they look old and don't look bulky like spade connectors) For 2 wire tail lights, I make one wire male and the other female. You can't make a mistake connecting them. On the 3 wire head lights, I make one wire connection about an inch farther down the harness than the wire with the same connector. Stevie Wonder can hook up my lights or a fat old man (me) in the dark.

One side benefit, you can wire up different H/lights (stockers, Guides or E&Js) and change them like a woman and her shoes...whatever mood you are in.:D

[rich^vic]

If you switch the battery at the ground, you effectively remove it from the circuit in every possible way. It's the battery with it's wild power output potential that turns a wiring job south in a hurry. The ECM and Radio will reset to their base state when you reapply power. The only other source of power will be the filter capacitors in the car stereo and the ECM. those capacitors will discharge very quickly into the car's wiring if they aren't internally diode protected (which they are so you don't shock yourself when unhooking the devices or destroy your ecm or radio when you short something out in the wiring harness). Even if they don't have this failsafe, Stero and ECM filter caps will not have the power to actuate the starter unless you have a stiffening capacitor rack in your trunk. I think that's a non-issue in any structured wiring consideration. If you do have a filter cap rack, it should be ganged with the battery cutoff switch no matter where you put it. It should also be noted that there is no 'live' wire in DC. Both positive and negative are required to complete a circuit and therefore they are both equivalent to an ac live wire. My reasoning for wiring it this way is that the less wires you need to gang together, the better. With a single lead being cutoff, you don't run into reliability issues with your starter and main wiring leads which are usually soldered to the positive battery post on negative ground systems. I've attached an image with this post.

-Richard


In doing so, you've just bypassed the kill switch with the internal circuitry of your radio and ECM and those wires aren’t anywhere sufficient to carry the load of the starter motor which WILL operate when you turn the key regardless of the position of your kill switch.

[Digger_Dave]

..... Im also going overkill on the grounding of the car (block to chassis, batt to chassis, chassis to body front and rear and each component individually grounded to clean, fresh unpainted metal. ....

I have the starter solenoid/fuel pump and brake lite switch under the floor and am wondering if I should use die electric grease to keep corrosion off the connections that are exposed to the weather?? Do you just put the stuff on the connections and thats it? How does this stuff work?

Rat

Rat, something to consider.

When I put together a wiring harness; I use a # 10 gauge wire that runs from front to back and COLLECTS ALL the grounds. (light sockets, any device that needs a ground) The #10 is attached to the ground post of the battery. It even runs to the dash. (assuming electric gauges; or at least for dash lights)

The two battery cables run from the battery; the ground attached to the block. (I use one of the starter bolts) The hot to the starter solinoid.

Although it's common practice to ground everything to the frame; that means at every place a ground connection is made, the paint (or worse yet, powder coat) must be ground away to make a good connection, and is now a point where corrosion can start and make a POOR conection.

But eliminating ground connections to the frame or the body the paint (or coatings) doesn't need to be damaged.

The dialetric grease is used (sparingly) between the connection and the point of connection. It has a degree of condutivity and prevents oxidation from forming in the connection.

Taillight sockets are probably the worst components to get a good ground at.
If you check some of the auto supply stores, they have replacement sockets with a ground lug comming off the side. Look at some of the newer cars in the bone yards, because of all the plastic panels that are used, they have taillight sockets with ground lugs.

[nzsimon]

It is not a good idea to tin then crimp as the wire is now solid and cannot be squished into every crevice of the crimp joint

By all means solder afterward but not before

[Digger_Dave]

It is not a good idea to tin then crimp as the wire is now solid and cannot be squished into every crevice of the crimp joint

By all means solder afterward but not before

This approach is based on the fact that the terminal end WILL be soldered after the crimp is made. Pre tinning the wire allows for a faster solder joint.

If the crimp joint is done with the proper tool (the one intended for the terminal ends being used) a good joint can be made, even with solid wire.

[Digger_Dave]

The ground terminals on new cars have a ribbed pattern on both sides.

FWIW, I'm still seeing ribbed terminals and star washers on the relatively new cars I'm disassembling in the shop on a daily basis. Winter weather is great for my current line of business -- collision repair.

Skip, I have been a long time user of AMP* terminal ends and almost all of them have the ribbed pattern on both sides.

After reading your response, I wandered out to take a closer look at some of the ground connections on my 2000 Dodge Dakota.

Seems Chryco doesn't totally agree with GM; found star washers at a number of ground points!!

* For those that want one of the best line of terminal ends, AMP (Aircraft, Marine Products) make ONE PIECE terminal ends; they don't have the split on one side.
And their crimp tool is the best in my experience.

[Deuce Rails]

This is a great post.

Just got Streamline's new catalog, it has some in it.

Does Streamline have a website? Where can I get one of their catalogs?

[Tudor]

looms man - use that cool pink plastic stuff with the slit you get from autozone :eek:

I have also run all my wires in that nice tarred cotton wire loom - it is a mother to pull the entire branch through a 3/4" loom sometimes, but it is worth it - it protects the wires, looks factory and old timey.

haywire has different sizes by the foot. I bought a ton of it at the lst swap I was at.

[Digger_Dave]

I have also run all my wires in that nice tarred cotton wire loom - it is a mother to pull the entire branch through a 3/4" loom sometimes, but it is worth it - it protects the wires, looks factory and old timey.

Tudor, a trick for pulling wires through the tarred loom.
First; arrange the wires that are going in the bundle to be as parallel as you can.

Tape the bundle at about 6 inch intervals.

Push a piece of welding rod through the loom with a loop on the end. Using the longest wires in the bundle; hook them through the loop of the welding rod, bend them over, and tape them tight. Tape the shorter wires so they form a bullet nose.

This next step goes best if you have a helper.

Holding the entrance end of the loom, Put a liberal amount of dishwashing detergent on the wire bundle and have your helper start pulling the welding rod through the loom as you guide the bundle into the loom.

[desoto]

If you switch the battery at the ground, you effectively remove it from the circuit in every possible way. It's the battery with it's wild power output potential that turns a wiring job south in a hurry. The ECM and Radio will reset to their base state when you reapply power..

But that's the point. Resetting the ECM back to it's base state means that you have to go through the entire learning process all over again before the engine will run correctly and you have to reset all of your radio station presets every time you re-apply power.

To prevent this disruption in these two systems, both sides of the circuit must be connected to the battery at all times.

If you connect these two critical devices permanently to the battery and put the battery kill switch in the negative (earth) side of the circuit, the whole vehicle is now earthed/grounded through the cases of the radio and ECM. As soon as someone turns the ignition key to the start position without, first, switching on the kill switch, all the current drawn by the starter moor will be shunted to earth through the radio and ECM.

the only way around this delima is to isolate the ECM (impossible, by the way because it's connected to the engine) and the radio from chassis earth.

If the kill switch is placed in the positive (live) lead, the radio and ECM power sources can be tied to the battery side of the kill switch and nothing will happen when the ignition switch is turned on before the kill switch is turned on but the radio and ECM will not have to be reset every time the kill switch is turned back on.

[Tman]

But that's the point. Resetting the ECM back to it's base state means that you have to go through the entire learning process all over again before the engine will run correctly and you have to reset all of your radio station presets every time you re-apply power.

To prevent this disruption in these two systems, both sides of the circuit must be connected to the battery at all times.

If you connect these two critical devices permanently to the battery and put the battery kill switch in the negative (earth) side of the circuit, the whole vehicle is now earthed/grounded through the cases of the radio and ECM. As soon as someone turns the ignition key to the start position without, first, switching on the kill switch, all the current drawn by the starter moor will be shunted to earth through the radio and ECM.

the only way around this delima is to isolate the ECM (impossible, by the way because it's connected to the engine) and the radio from chassis earth.

If the kill switch is placed in the positive (live) lead, the radio and ECM power sources can be tied to the battery side of the kill switch and nothing will happen when the ignition switch is turned on before the kill switch is turned on but the radio and ECM will not have to be reset every time the kill switch is turned back on.

Come on Skip, Radio? ECM? What are the spaceage things you speak of?:D I have made it a point in the last week to ask the kill switch question to several other guys in the know. I am leaning towards the Negative side, this is on a bare bones car, no computers.

[Digger_Dave]

I have made it a point in the last week to ask the kill switch question to several other guys in the know. I am leaning towards the Negative side, this is on a bare bones car, no computers.

I have to aggree with Skip.

Another thing that can happen if the ground (-) is used for switching battery power OFF.

If it isn't turned ON, and you try to start the engine, the ignition curcuit can become the ground and with the load of the starter trying to pass through; it WILL fry points and possibly the coil. (and it won't take more than a couple of milliseconds!)

I would put the Master Cut-off Switch in the HOT (+) battery cable.

[Tudor]

Yeah Digger - all that does the ticket, It is hard sometimes, but worth it. - I remember I didn't have a helper, I think I ended up using a long piece of rebar tie wire to pull the wire with. I made the tie wire longer than the loom had to be for that run, then you run the wire through the loom and tie it off to something sturdy. Then pull like hell to get the loom over the wire.

The soap would have helped!

You really only have two lpng runs - 1 to the front and 1 to the back..

[Digger_Dave]

Yeah Digger - all that does the ticket, It is hard sometimes, but worth it. - I remember I didn't have a helper, I think I ended up using a long piece of rebar tie wire to pull the wire with. I made the tie wire longer than the loom had to be for that run, then you run the wire through the loom and tie it off to something sturdy. Then pull like hell to get the loom over the wire.

The soap would have helped!

You really only have two lpng runs - 1 to the front and 1 to the back..

This might not be the time to mention it; but the loom IS available in different sizes.

The soap will actually dry up after a while, and the harness you created will hold its shape.

I remember pulling one bundle through the loom that was tied to the work bench, wasn't paying attention and pulled the bench over!!

[WZ JUNK]

I have to aggree with Skip.

Another thing that can happen if the ground (-) is used for switching battery power OFF.

If it isn't turned ON, and you try to start the engine, the ignition curcuit can become the ground and with the load of the starter trying to pass through; it WILL fry points and possibly the coil. (and it won't take more than a couple of milliseconds!)

I would put the Master Cut-off Switch in the HOT (+) battery cable.



Okay, I am confused. If you have one ground wire from the battery and you put a switch in that wire to disconnect the battery. How will current flow anywhere in the circuits with the switch in the disconnect position?

[Missing Link]

Okay, I am confused. If you have one ground wire from the battery and you put a switch in that wire to disconnect the battery. How will current flow anywhere in the circuits with the switch in the disconnect position?

Because some components contain their own grounds. Some components ground through their mounting brackets, case, etc. Some even have their own ground wire. The component would create the ground for the circuit. The component's ground would be, more or less, replacing the negative battery cable. This would allow the circuit to complete itself virtually by-passing the shut off.

I look at the shut-off as eliminating power, not eliminating ground. If I am messing with something electrical I certainly don't want power getting to it. Shutting off power via the + battery cable will not allow power to the vehicle and after all isn't that really what we want that switch to do; Eliminate power.

There is no way I would put a shut-off on the negative side of the battery. Too many ways for that to fuck up your whole campaign.

[WZ JUNK]

Because some components contain their own grounds. Some components ground through their mounting brackets, case, etc. Some even have their own ground wire. The component would create the ground for the circuit. The component's ground would be, more or less, replacing the negative battery cable. This would allow the circuit to complete itself virtually by-passing the shut off.

I look at the shut-off as eliminating power, not eliminating ground. If I am messing with something electrical I certainly don't want power getting to it. Shutting off power via the + battery cable will not allow power to the vehicle and after all isn't that really what we want that switch to do; Eliminate power.

There is no way I would put a shut-off on the negative side of the battery. Too many ways for that to fuck up your whole campaign.

It still seems like the circuit would have to go back to the battery to be complete. You seem to be saying that the circuit could somehow work without the negative side of the battery hooked up if I am understanding correctly. If you have one positive battery cable and one negative cable to your battery, I think you could put the switch in either the positive or negative cable. Either way you are eliminating the battery and shutting off all power. If you have additional wires besides your main cables attached to you battery, then I would agree that the positive cable is the place for a shut off switch, but I can not imagine making extra connections directly to the battery.

[Digger_Dave]

Okay, I am confused. If you have one ground wire from the battery and you put a switch in that wire to disconnect the battery. How will current flow anywhere in the circuits with the switch in the disconnect position?

The problem occurs when any device that is normally grounded, ignition points as an example, which are grounded on one side, TRY to find the other side of the battery. (negative side)

When the starter is engaged without a ground (it becomes a floating ground) it throws a HUGE amount of current via the POS connection through the smaller components. They aren't able to handle the "inrush" current and get destroyed.

[Tman]

It still seems like the circuit would have to go back to the battery to be complete. You seem to be saying that the circuit could somehow work without the negative side of the battery hooked up if I am understanding correctly. If you have one positive battery cable and one negative cable to your battery, I think you could put the switch in either the positive or negative cable. Either way you are eliminating the battery and shutting off all power. If you have additional wires besides your main cables attached to you battery, then I would agree that the positive cable is the place for a shut off switch, but I can not imagine making extra connections directly to the battery.

Agreed John. Using their same logic would mean you couldnt touch the positive post at all, you would get shocked:D

[WZ JUNK]

The problem occurs when any device that is normally grounded, ignition points as an example, which are grounded on one side, TRY to find the other side of the battery. (negative side)

When the starter is engaged without a ground (it becomes a floating ground) it throws a HUGE amount of current via the POS connection through the smaller components. They aren't able to handle the "inrush" current and get destroyed.

To paraphrase your thought, you mean that even if the negative battery cable is unhooked and no other circuits are hooked to the negative side of the battery, and I hit the starter switch, there is current flow. I do not think we are talking about the same thing. Sometimes typing out our thoughts do come out exactly what we mean. Of course I have a bad cold today, who knows what I am thinking. I have great respect for your knowledge in this area, it is just a new line of thinking or logic for me.

[desoto]

Come on Skip, Radio? ECM? What are the spaceage things you speak of?:D I have made it a point in the last week to ask the kill switch question to several other guys in the know. I am leaning towards the Negative side, this is on a bare bones car, no computers.



....and, with a spanner laid across the battery terminal to the frame, I can make your car fully functional. A battery jumper cable can make it a permanent jury-rig. Can't do that with the swtch in the positive cable, though. (unless you can get to the kill switch and jump the contacts.

I've been wiring cars since the mid sixties and the only time I've ever put a kill switch on the negative cable was in a 6 volt, positive ground, system.

A kill switch in the ground circuit is the easiest thing to get around. All you need to do is run a jumper from the negative post to ANYTHING that's part of the chassis.

A kill switch in the live side is a lot tougher to bypass. If you can't get at the kill switch, you have to run a cable from the positive lead all the way up to the starter-end of the battery cable.

[Tman]

....and, with a spanner laid across the battery terminal to the frame, I can make your car fully functional. A battery jumper cable can make it a permanent jury-rig. Can't do that with the swtch in the positive cable, though. (unless you can get to the kill switch and jump the contacts.

I've been wiring cars since the mid sixties and the only time I've ever put a kill switch on the negative cable was in a 6 volt, positive ground, system.

A kill switch in the ground circuit is the easiest thing to get around. All you need to do is run a jumper from the negative post to ANYTHING that's part of the chassis.

A kill switch in the live side is a lot tougher to bypass. If you can't get at the kill switch, you have to run a cable from the positive lead all the way up to the starter-end of the battery cable.

I understand your reasoning for theft. My touring is an open car, if they want to pull the tonneau cover off they can get to the whole damn thing!

Lets change the direction here a bit. Which side is the best side to attatch the kill switch if all you are worried about is a quick switch in case of fire?

[desoto]

If either side of the battery is COMPLETELY disconnected, no current will flow PERIOD. You’re not going to burn anything up if EITHER side of the battery is COMPLETELY disconnected.

If you put in a device that requires constant power, you should NOT put the kill switch in the ground cable, otherwise you’ll burn out the device that you have connected to the battery via a bypass circuit.

If you need to bypass the kill switch, put the kill switch in the live lead, not the ground lead.

Bypassing a hidden kill switch is a no-brainer if the switch is in the ground circuit. You can do it with ANY piece of metal that will bridge the gap between the battery and the chassis/steel body.

[Tman]

Skip, I want to thank you and everyone else for the input on this thread!

What would you say about a kill switch on BOTH the Pos and Neg sides?

[Mutt]

As a FYI, NHRA requires the switch on the power side.


Mutt

[Digger_Dave]

What would you say about a kill switch on BOTH the Pos and Neg sides?

Are we talking about a single switch with TWO SEPARATE CIRCUITS? Or TWO separate switches?

TWO curcuit switches DO exist, but they are VERY expensive. (and bulky)

Skip points out that if NOTHING bypasses the Master Cut-Off Switch (MCS) then the situation I refered to WILL NOT HAPPEN if the switch is in the GROUND cable.
And he is right.

A total cut-off of the ground would not cause any problems.

Using a single curcuit switch in the positive battery cable (assuming NEG ground) will "kill" everything, unless you bypass the switch (on the GROUND side; BAT) for things like radios that have memory presets, (which I do) or EMS's (if you have any) AND in my case, interior lights. (it helps to be able to find the master cut-off in the dark; it's under the seat!)

AND, it prevents any damage to smaller components in the event you forget to turn ON the MASTER CUT-Off before trying to start the engine. (I do suffer from CRS!! )

But the drift of the questions had me thinking as I replied, that certain devices would be by-passing the MCS in the GROUND cable; so the situation I described, COULD happen.

So ... if your not sure what will (or won't) by-pass the MCS; then I would put the the switch in the POS (+) battery cable. (assuming NEG (-) ground)

There are "keyed" MCS's, but most of the ones I have found, could be picked by an 11 year old kid!

One trick I have done is to mount the MCS in a totally enclosed box, holes (with grommets to protect the cable) comming out the side. This way some smart ass can't just wind a couple of turns around the two posts with a coat hanger and "jump" the switch.

One last warning. Make SURE the engine (starter) is WELL grounded. I'm a big believer of running the ground cable DIRECTLY to the block. (usually off one of the starter bolts) Especially if the battery is in the back. (trunk) Use LARGE cable (smaller cable sets up resistance)

Then a ground strap to the body from the block.

A situation that I was asked to investigate for an insurance company turned out to be the LACK of a good ground to the engine.

New car, fresh engine. Battery grounded to body, but not a good ground from the body to the engine. (new motor and trans mounts can insulate the engine from ground)

The moment of the first "firing." Throttle given a couple of pumps, starter engaged. Engine fires; and REVS to about 6000 RPM!

It seems that the throttle cable took the load of the starter and MELTED in the WIDE OPEN position!! Engine "lunched!!"