I'm in the process of wiring the roadster. Like everything else, I'm starting from scratch. Below is my crude attempt at a schematic for turn signals and brake lights. I'm using '39 Ford LED taillights out back and motorcycle turn signals up front. I'm also using an LED 3rd light bar imbedded in my rollbar. Turn signals will be controlled by an SPDT toggle switch and an LED compatible turn signal flasher relay. Couple of questions; Does my schematic look right? And if so, how do the turn signals and brake lights work on the same circuit? Does the LED flasher override the brake light switch or vice-versa? Also, can the flasher and B/L switch both be tied into the 'always hot' circuit at my fusebox? Any help is greatly appreciated!
Won't work the way you have it drawn out, as brake application will always illuminate both rear lights along with the front lights, and either signal application will cause all four lights to blink. To use a regular toggle switch, you could use a relay set-up like used when using a old time three wire signal switch. An alternative would be to mount a regular aftermarket signal switch under the seat or dash. Either way, the third brake light needs it's own feed from the brake light switch, independent of the signal switch. Someone does make an electronic box controlled either by a momentary toggle or their column switch that will do what you want (and is timer cancelled); but it is $$$. Usually the brake light circuit is wired hot constant, while the signal circuit is wired hot key on.
That's not going to work as you intend / wish for. There's nothing overly clever in an LED flasher unit - it just flashes without the load provided by regular bulbs. I think what will happen with your schematic is that with the flasher on, all of the lights, both sides, front and back, will come on solid when the brakes are applied. You need the kind switching as found in a GM column for instance or one of the aftermarket turn signals. Or it can be achieved with appropriate relays. There may be other ways. I'm no expert though! Or, with some modification and separate indicator lights on the rear what you have can work, European style. Chris
Speedy Bill sells a real neat electronic unit with two push buttons and you can control the length of time the signal will flash by how long you hold the button. They automatically cancel after your chosen time length. Much better than toggle switches. Just my opinion.
Thanks for setting me straight! I think I've found something but it kinda falls under the old 'too good to be true' adage. Here's a company that makes '39 Ford LED's with a 4-wire connection that effectively separates the brake and turn signal circuits. $99. Opinions on this, please! http://www.cool-leds.com/6020-39 Ford Install.pdf
They don't work well IMO because when both your brake and turn lights are 'on', the brakes compete with the turns and wash them out. My avatar was wired like that (separate brake/turn lamps) when I got it, and people behind me commented that my turns weren't clearly visible when the brakes were applied and it was confusing. I removed the separate brake lights and wired everything though the turn signal switch and that fixed the problem. You need at least a six wire turn signal switch if you want the brakes/turns to share the same lamp. It's possible to use a SPDT switch to do what you need, but you need to add a couple of 2PDT relays controlled by the switch to separate the circuits. If you want a single dash indicator light, make those 3PDT relays. Add a DPST switch and you can have emergency flashers too. If you need help with the diagram, let me know.
Here's the wiring diagram to use a SPDT switch with relays to share the brake/turn lamps in the rear... Ok, so my drawing skills ain't what they used to be... In a nutshell, your power from the brake light switch connects on one set of contacts (one pole) per side, a normally-closed (NC) set. Your REAR brake/turn lamp will connect to the 'common'. Your 'flashed' power for the turns from the flasher will connect to the normally-open set on EACH pole, and the front turns will connect to the other common. If you're only running front/rear turns, all you need is two 2 pole relays. If you wish to use a SINGLE dash indicator light as shown, you'll need 3 pole relays. If you opt for two dash lights, simply connect them to the front turn lights. A 'third' brake light will connect to the brake light switch. The relays you should be able to find at any electrical supplier who services industrial customers. Make sure you ask for 12V coils. They typically come with pins, you want the matching base (much easier to terminate). These are commonly known as 'ice cube' relays (denoting their shape/size) and should cost give-or-take about $25 each with the base. The 3 pole may be easier to find than the 2 pole. If you can't find them locally, McMaster-Carr has 'em; 7170K41 (relay) 7122K19 (base) for the 2 poles, 7170K44 (relay) 7122K21 (base) 3 poles, at about $18 for the 2 pole w/base, about $25 for the 3 pole w/base. Contacts are good for 10 amps each set, plenty for this use. Buy a spare for 'just in case'... If you want to add an 'emergency flasher' function, connect a 2PST switch as shown. You'll need a flasher that can flash any load, but that should be it. One difference from a 'regular' turn signal switch is when the e-flashers are on, the 'regular' brake lights won't come on. Any questions, I'll be glad to answer them.
You can also do a relay set-up with 5 pin relays, a few more wires; but the relays are readily available at the local auto parts store. You can use a three terminal flasher and use the pilot terminal to work a dash indicator; or if you want two indicators, hook them to the front signal terminals. If you have single wire front lights; you can run the parking lights thru the center pin (87A) on the front relays and have the light function as both a signal and park light.
Let me offer up a system that I am using in my 40 coupe. This system was easy to install and if used with the toggle switch option is completely hidden from view thus allowing your car to look old school while providing an adjustable self canceling system. If you enjoy the challenge of wiring up your own system which is great then ignore this advice. The wiring advice offered so far on this thread is awesome as usual and After two years of using this system I have found that using the toggle under the dash is a little inconvenient and that the nice column mounted switch this company offers would be a good choice. http://www.turnswitch.com/Turnsignal.htm
This is electrically the same as what I posted, you're just using 1 pole relays. Considerably messier for wiring and will take up more space though... If you install jumpers at the ice cube relay bases, you'll only have six or seven wires total going to both relays. And replacing a relay is a simple unplug/plug in deal. I used this on a motorcycle where I had single-function front running lights, a LED indicator built-in to the speedometer, and two brake/tail lights. Mounting space was at a premium too, the 3 pole relays took up less space.
Guys..............very nice! Thank you so much! I'm more familiar with the 5pin relays. Rich B, excuse my electrical ignorance but I thought 85=ground, 86=to switch, 87= to device, 30= main power. Does your wiring just reverse the contacts from N/O to N/C? Also, I have a 3 position toggle switch with the center/off position going to 'load' on the flasher. Yours goes to ground and I'm sure yours is right. Can you explain, please?
85 and 86 are the relay coil connections. 87(NO), 87A (NC), and 30 (COM) are just contacts and can be tasked however you need them. All lights will connect to a 'common' (30), and you're switching the input power to them. The NC contacts is for the brakes lights, NO for all turn functions. And there should be no ground at the SPDT switch. Don't be afraid of the ice cube relays; there's a schematic printed on each one, numbering each contact connection, with the corresponding numbers on the base. Actually easier to wire compared to the typical Bosch relay in a deal like this...
Some 5 pin relays have a internal diode across 85 & 86 to prolong the life of control switch contacts; in that case maybe there is a preferred polarity; but it doesn't really matter here. My drawing uses 30 as the light output and 80 & 87A as the inputs. You can't use the flasher output (load) to operate the relays as it is one of sources you want to direct to lights (the other source is brake light switch output). You can either switch ground as I have shown; or power as in Steve's circuit; just have to follow the appropriate schematic. I drew mine up for use with old three wire column mount switches and I guess I would rather put ground thru them than power. I guess I prefer the 5 pin relays because you can get them at the corner store and besides I learned to dislike the socket mount relays is dealing with lots of relay and socket failures in garbage trucks before the age of PLCs. They did not seem to me to be mobile friendly, then again the environment was much harsher than they would see in a car. The cube relays would probably work just as well for you. Maybe see if available with retention bails. I don't necessarily think that four 5 pin relays would take much different space the two DPDT or 3PDT relays and sockets. Micro 5 pin relays would also work, if space is at a premium. There is more wiring with the 5 pin relays; couple more coil terminals and jumpers. Here's a crappy poor angle pic of the panel in my coupe; four relays for the signals, a relay for the horn, another for ignition (to minimize load on the '35 ignition switch contacts), and a two prong flasher. A little hard to see since all the wiring passes by it.
I've used ice cube relays in both cars and motorcycles (paint-shaker rigid-mount Harley Sportsters no less... buy Loctite in quantity, LOL...) with no issues. They don't like moisture so need to be mounted somewhere dry, and I do use a retaining strap in most cases, it's simple enough to fab one.
OK, between both of your schematics I think I've got 99% of it figured out. With Rich's I can see the wiring and with Steve's I can see the functions. 2 questions. I assume I can use my existing 3-wire LEDs and don't have to buy the 4-wire units. Also, where do I connect the OFF terminal of my 3-position toggle switch?
Yep, you can use the 3-wire lights. As to the switch, how many terminals does it have? Just three? If so, it's not an 'off' terminal, it's the 'common' and should be marked 'com'. Depending on how you power the relay coils will determine what gets connected to it. Rich's diagram uses unswitched 12V power to the relays and switches the ground connection to operate the relays. If you go that way, then connect the common to ground. My diagram is opposite; I'm switching the 12V power, so you'd connect 12V power to the common and the other side of the relay coil connects to ground. There's advantages/disadvantages to each method, either will work, so it basically gets down to which way you want to do it.
Thanks for all the info and diagrams. You guys have cleared it up for me! Gotta go pick up a few relays and I'm gonna get on this wiring thing next week. Again, thank you very much! Once again, the HAMB comes through!
There is always the infamous trailer converter out there too! It take turn signals and brake signals in and combines the functions. Just make sure you get one that is LED compatible.
This might not be HAMB friendly, but I went with a GM steering column and wired it with standard GM plug pinout. Gave me emergency flashers, cancelling turn signals, dash indicators and combined brake lights with turn flashers as so I could go with 4 wires to the rear (also a horn button where people expect it). I basically cut and spliced two trailer kits together to get it the back, so it's a nice clean install and it works great except for third brake light which I connected to my left hand turn signal so it blinks when I'm turning left. Could have run another wire for that I guess had I thought about it. It's really pretty close and I am probably the only guy that notices. It does bug me though, so I am thinking that I could get it to work right without the extra wire by connecting both turn signals using in-line diodes to the third light. Anyone ever try that? Will it work?
Your circuit will work if you consider running auxiliary light assembly for rear indicators. I used motorcycle signal units. So tail light and brake in one unit and signal as rear stand alones. I wired up my AH Sprite that way. In fact the Sprite beehive surface fixtures are pretty much go with anything style. Assembly 80 red lenses. https://mossmotors.com/mg-midget-au...ectrical-ignition/lamps-lighting/bugeye-lamps
It will work; but may "bug" you twice as much; as the third brake light will flash with either left or right signals until the brakes are applied, probably as distracting to other drivers as is your current set up.
Probably too late for your use, but I used this toggle switch system and was very happy with it http://kwikwire.com/toggle-turn-signal-switch-with-wire-harness/
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