Need help with LED tail lights

pgerhardt

pgerhardt

Well-known member
Ok. So spent all day working on my tail lights without success. I ordered replacement taillights that were already set up with LEDs. The left tail light had stopped working at all. The good news is that I got that one working working. It was a bad ground. I just ran a ground wire from one of the square nuts holding on the taillight bracket to one of the bolts holding on he rear fender. That solved that problem.

The real trouble happened when trying to set up the turn signals. The setup seemed very simple. There are two wires that come back from the wiring harness - one green, and one black. They are for the brake (upper), and running (lower) lights. The person who had set up the turn signals for my car followed a similar pattern running a green (plastic coated) wire back for the left turn signal light, and a black wire for the right turn signal light. I connected the wiring harness green and black wires to the tail lights (right one via the crossover harness), and I had brake and running lights. Great!

Now for the turn signals. I made up my own cross over wire for the black (right) turn signal wire. Then made up 2 two into one adapters so each tail light could receive both the turn signal wire and the wire from the harness. Then I connected everything up. Now when I put on either turn signal, both tail lights flashed, while the third tail light in my back widow worked properly!! (It’s wires also tap into the green and black turn signal wires.)

Now for the really weird stuff! If I disconnected both the wiring harness wires from the right tail light then both work correctly for turn signaling. Maybe (just guessing here) the LED tail lights require so little current to operate that some is leaking back through the regular harness causing both to flash?? I am beginning to think that with LED tail lights you can’t use them for turn signals, and I should go with separate turn signal lights in the back like I have in the front. Without a good idea from our collective ‘model A hive mind” to put me on the correct path, that is the route I will take.
 
I bought some "one way wire" and used that to keep current from flowing back from the turn signal light to light up the other side. I recall it came from Radio Shack and it had the effect of a diode in that the turn signal current went to the turn signal bulb but wouldn't come back through the running lights or any other light. Don't think it was expensive but it had been years. I was using the rear Brake lights as the turn signal, not separate lights. When I activated the lever for a left turn the left brake light would blink and the right one would just come on steady if I was on the brake. It can be done but I have forgotten how. I know I drew it on a piece of paper and went to the elecronics store and told the clerk what I wanted to do. He showed me how in no time right on my drawing. It wasn't complicated then, but now, wow would it be a challenge.
 
Setting up LED rear lights is easy. The problem now is that I guess I don't quite understand what you have done. What turn switch are you trying to use ? If you don't have a wiring diagram with/for it then one should be able to be found on the internet easily.

The brake lite is also the turn lite. They use the same filament.

You are right about the LEDs drawing far less current but that only affects the flasher. Higher wattage/CP front bulbs corrects that problem. [ Or a 6v electronic flasher if you can find one, I guess they can be had from Europe].
 
If you have both the left and right signal light wires connected to the third brake light, as you described, that would be where the cross-connection is. Any brake or signal application would end up illuminating both the left and right lights.

The third brake light should be connected to the brake light wire before it enters the signal switch.
 
rich b said:
If you have both the left and right signal light wires connected to the third brake light, as you described, that would be where the cross-connection is. Any brake or signal application would end up illuminating both the left and right lights.

The third brake light should be connected to the brake light wire before it enters the signal switch.
Click to expand...

The third brake light in my rear window also functions as a high bright turn signal. Only the right & left turn signal wires of the the third brake light are connected to the turn signal wires coming from the front.

I thought of using diodes to direct the flow of electrons, but decided using separate turn signal lights would be easier and ordered a pair.

Sleeping on the problem, I came up with a temporary daytime solution until my turn signal lights arrive. Treating each tail light as two (top & bottom) separate lights, I connected the brake light wire to the top of each tail light, and the turn signal wire to the bottom. I now have brake and turn signals, but the running lights don’t work correctly. That will do until my signal lights arrive from Snyder’s.

Thanks everyone for your responses.
 
The brake light wire goes thru the turn switch and on to each stop light. [top light].

Personally, I just think you are making a lot out of this. The normal lights work just fine as brake and turns without the extra wiring. I asked a question, but,,,,, without an answer its hard to give an answer.
 
With original wiring, battery is connected to the stop switch, the other side of the switch runs back to the stop light(s), upper bulb. When adding turn signals, that other side of the stop switch is disconnected and another wire run from that point to the turn signal switch, where it is then distributed to the two stop lights over two new wires (the disconnected wire may be reused for one of them).

Your OP suggests you may have connected the TS switch in parallel with the brake switch, which may be the problem. In any case, using separate lamps for signals will eliminate the brake circuit from the mix. Just make sure your brake switch is connected directly to the stop lamps and not interrupted by the TS.

Also, your third brake light won't be able to connect as turn signals, except maybe with diodes.
 
What does your system use for a flasher? The "mechanical" style that has been around since flashers are notorious for not working with LED's.
 
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