LED turn signals only work without headlights / running lights on

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loudog_jones

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I've looked over some older threads, but didn't see anything quite like what I'm having issues with.

I installed some new tube-style fenders that came with LED turn signals built in. I installed a new LED compatible flasher relay and now they only work if my headlights and running lights are off. I don't get the hyper flash, so I assumed the relay worked. I have the LEDs wired up to the side marker wires, as I'm going to install some JK turn signals in the grill CJ style. I did, however, wire the LEDs up to the front turn signal wiring today to test, and the issue was the same.

I'm using the LM470 relay from AutoZone, it says LED compatible and up to 6 lamps. Rear lights are stock.
after_fenders.jpg
 
The side marker lights have an alternating ground, so depending on how they're wired, they'll only work with the lights either on or off.

You could get a 3 wire LED light, wire up 2 lights in series, or mess with diodes and wiring. When I installed my tube fenders I went with 2 lights as I couldn't find 3 wire ones at the time, and I didn't feeling like frigging around with diodes and the wiring.

You can have a read about it here: goo.gl/t1WUBT
 
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loudog_jones said:
Thanks for the heads up, I just read through that thread. He's got some very helpful info in there. I'm going to try some of this and report back with results in a few days.
Click to expand...

Glad you found it. I look forward to hearing your results!
 
The easiest solution is to place a 3 wire led in the front flat fenders and ditch the side markers. The front LEDs can be seen from the front and side of the Jeep and they are super bright, the side markers become somewhat redundant. And I pass inspection no problem.

The front LEDs work so well I would reconsider drilling holes in your grill and going with the JK mod. I think that has become unnecessary now.

3 Wire Led (Dual Function Running Light\Turn Signal)

JEEP \ LED

Black = White
Black\Yellow = Black
Tan or Green = Red
 
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Side marker LEDs have a problem because the voltage in that circuit changes polarity (direction) depending on the position of the headlight switch. It can be resolved by installing a small "bridge rectifier" that always provides the same polarity to the LED light no matter what polarity the bridge rectifier is receiving from the circuit.

Bridge rectifiers are pretty simple small devices that can easily be wired in to insure the LED always receives the correct polarity.

Here's an example of a couple small compact rectifiers and the magic circuit that fixes the problem. Fry's carries them. That little blue circle on the left side of the schematic is showing the side of the circuit with the alternating polarity. The "Load" on the right side would be the LED that would now only see the correct polarity at all times.
Bridge rectifier 2.JPG
Bridge rectifier.JPG
Bridge Schematic.jpg.JPG
 
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Maybe some on can link me to a post that might fix our issue. Helping a friend with a 2002 TJ. He had 3 wire leds in the front tha flashed but very fast. I installed led taillight assemblies in the rear. The turns would not work with the headlights on, so I told him to get an led flasher and it should be ok. Installing the led flasher did not work at all. I switched back to the old flasher and still nothing. Nomturns no hazards. The original flasher made some noise once but that’s it. Now the brake lights will not work with the hazard button pushed down. After all this I decided to clean things up up front , so I cut all the original wires for the front markers back so that are just 4 wires left. I wired led/TJ. White to black, And black to black with yellow. I left the red unconnected because I have no power to verify if the gray is supposed to be the turn signal. Did we get a bad flasher have be burnt something else up? I checked the fuses but can not find a bad one. Lots of electrical experience but zero TJ. also it has DRL of some type, it looks like the headlights are getting reduced voltage until you turn then on. Today we had fast flashing signals for a minute, but only with the key off. I could not get them to work after that, still no hazards either.
 
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Have not made it back over there to diagnose further. I am waiting for the super duper Gold Coast flasher unit to arrive to see if that fixes anything. I now believe that there must be a bad fuse or connection. Looking at the wiring diagragm, there is no reason we should not have power to the grey and Tan wires up front. I have to figure out what the forth wire I have is for,,,thining fog lights but need to see colors,,
Screen Shot 2019-01-07 at 11.50.50 AM.png
Screen Shot 2019-01-07 at 11.50.50 AM.png
 

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I had this issue when I installed my flat fenders as well. I only had a two wire Led for the fenders. Turn signal wouldn't turn on with the headlights on and would without them. What I did was simply hook up the positive wire to the turn signal wire and then grounded the negative wire on a bolt on the flat fenders. Haven't had any issues with it since.
 
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Please read post #11 above for an explanation of what is causing the problem when LEDs are installed as side marker lights.
 
InfamousCanadian said:
I had this issue when I installed my flat fenders as well. I only had a two wire Led for the fenders. Turn signal wouldn't turn on with the headlights on and would without them. What I did was simply hook up the positive wire to the turn signal wire and then grounded the negative wire on a bolt on the flat fenders. Haven't had any issues with it since.
Click to expand...
Did you ground both the negative wire from the led and from the factory wire?
 
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