If you have 12 volts coming into the switch 24/7 , why have an additional “ switched” 12 volt coming in, only when the ignition is on. Most cars I have dealt with, the ignition has no effect on the light switch. I guess there could be a reason you would only want a light on when the ignition is on, using a double pole switch. It has been a while since I worked on a car light switch! Bones
Well there’s got to be a reason! Lol It just escapes me now. Maybe he had his own reason for something special? Bones
Yes I noticed that it doesn’t have parking lights. But I guess for a hot rod, maybe you don’t need any. Bones
Most ignition switches are designed to switch off the accessory circuit / headlight circuit when cranking the engine over. Leaving the headlights on with a continuous feed while cranking would kill the battery There is a "P" provision on the Headlight switch. Whereas the taillights work with Park and Headlight positions. A lot of cars also require the Ignition switched on for stoplights to work, which is a car guy hazzard [especially for those that need to tow rope their cars home on a regular basis]
Wiring 101 Once you let the "magic smoke" out, it is extremely difficult to get it back in................
Better get some extra smoke and the correct tools to install it. Preferably negative earth, English smoke. Sent from my iPhone using The H.A.M.B. mobile app
Ok, I get that about the cranking, but wouldn’t the light stay on while cranking if there is a non switched feed coming into the headlight switch. Or does that wire from the ignition switch only becomes hot while starting and kills the power to the lights during starting? I have seen that feature on some OEMs. That would make sense to me. But you would need a light switch that has this feature. For sure. Bones
The headlight switch in that diagram looks like an early '50s Ford headlight switch. It used two different power supplies. One for the headlights and the other for park, tail and dash lights, or something like that.
That is the best answer for having a drawn out wiring diagram of you car with your car. My buddy's old Model A roadster was wired by a guy who got a real bargain on some large rolls of red wire. All the correct gauge for the appropriate circuits but when you are laying under the car in a gravel parking lot trying to figure out why his tail lights aren't working on the way to a rod run it isn't fun to sort out. Come to think of it, I was just looking at a photo of wiring mess under the dash of a guy's truck on another forum trying to come up with a solution for him to make it more organized and add fuses without breaking the bank and it has almost all red wires.
I started with a wiring mess. Pieced together, undocumented, and there had been a harness fire at one point, repaired with butt connectors, ScotchLocks, and random wire bits. Most of the wires were at least different colors, but there were places where things like a green wire came off the fuse block, got spliced in to a black wire going through the firewall, and ended up a blue wire to the tail lights. I started diagramming it just to figure out what went where. Then I got out my dykes and the whole mess ended up on the floor. I went with new from Painless. Neatly run, schematics included, and my changes are documented for later. Sent from my iPad using The H.A.M.B. mobile app
A good resource for original wiring schematics is the Old Car Manual project. They have a number of them for 1965 and older cars. http://www.oldcarmanualproject.com/manuals/wiring/index.html
Brake lights are normally powered from an un-switched source. 4 ways, too if you go that way. Signals are usually fed from switched power so you don't leave the car parked with a blinker going. Many OEM headlight switches have two un-switched power sources; one fused to suit the tail/dash lights, the other heavier fused or circuit breaker protected for the headlights. Aftermarket switches usually have only one power; some people add a fuse after the switch for the tail/dash lights. Never have seen a car where the headlights go off when cranking; maybe new computer controlled cars do that. Pretty common to check a no crank problem by seeing what the headlights do when cranking. Wiring doesn't have to be a mystery and scary; just look at one circuit at a time instead of the whole thing and you can see how it all works together.
In response to the OP: Three radiator fan Sequential control scheme using two stage electronic controller and one electromechanical controller along with voltage booster relay directly from alternator through circuit breaker, integrated with compressor signal and with manual override switch. And yes it works like a champ!!
One thing that should be clarified; a diagram and a schematic aren't the same thing. A diagram will attempt to show the physical location of components in relationship to each other with the wiring in between them. This is what you'll typically see with 'whole vehicle' diagrams in vintage service manuals. The problem with these is as you add components, they get very 'busy' and the opportunities for error go up. It's rare not to find at least one mistake or ambiguity in these if the diagram is much more than a very 'basic' vehicle. A schematic will show the electrical relationship between components and is usually dedicated to a single circuit or system. For troubleshooting/circuit design purposes, much more useful and can be much less confusing. The issue with these for some people is wrapping your head around the fact that what may appear to be a short wire on a schematic may be a long wire in use and vice-versa. Generally speaking, if you're running a generator a diagram may be fine as charging system limitations will prevent you from adding much in the way of additional electrical accessories. But if the vehicle is equipped with stuff like power seats/windows, AC, emergency flashers, stereo/amps, etc, then schematics are easier to read. Now because both of these methods have their own shortcomings, what I prefer to do is have a diagram and schematics. The diagram shows physical locations of components and the harness layout/route but no individual wires shown. Identify each circuit from your schematics and note which circuit is in which branch of your diagram; you may even want to break it down further and identify individual pieces. As an example, a lighting circuit (head/park/tail) could be broke down as circuit 1, with head/park lights being 1A, tail 1B and dash lights 1C. All this takes some time, but can pay real dividends down the road when your memory may be a little fuzzy... LOL. The next owner will love you and I would think this would be a good selling point.
Drew this up when wiring my Model A coupe. Is'nt really elaborate as far as wiring goes but details color and gauge and is laid out roughly by location in the car. Used a Rebel kit, but basically a economical source of coloured wire in various gauges. Prints out on two 8 1/2 x 11 pages so it could be carried in the glove box in the dash. Handy for troubleshooting and a good source of info for the new owner. Canuck
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