LED Park Lights - Both flash

[dblessing]

I just installed new LED bulbs in the park lights on my 1966. I also installed the electronic flasher required for LEDs. These were LMC Truck part numbers 36-0362 and 36-0356 respectively.

Prior to installing the LEDs, the turn signals worked as expected with incandescent bulbs. Now, both sides flash regardless of whether left or right is selected on the turn signal switch.

Has anyone else encountered this issue specifically with LEDs? I reached out to LMC support to see if they've heard similar reports from customers but I'm not sure if they'll be much help.

Do I need a resistor somewhere on the circuit?

I will also recheck my grounds tomorrow. Could a bad ground on the flasher cause this? Or only a bad ground at the bulb socket?

[AZKen]

WHAT DO THE REAR LIGHTS DO? If just fronts are LED. Put original flasher back in. There is a polarity reverse procedure for some vehicles. Be sure you don't have hazard flash on.

[dblessing]

I replaced the tail lights with LEDs, too, and they flash correctly. This pickup does not have hazards.

I thought maybe one of the lights was leaking voltage through the ground, enough to light up the LED but not an incandescent. I turned the switch to the right and also removed the right socket and the left still flashed. So any electrical short/bad wiring is happening in the harness and not as a result of the ground, it seems. I'm not sure where to take it from here.

For completeness, I tried reversing the polarity on the flasher and it didn't work at all, so I'm reasonably confident the flasher is working correctly. And again, the new flasher works with the incandescents (and the rear tail lights).

[AZKen]

It's pretty simple to trace proper wiring. The turn signal switch is the "router". It gets power from stop switch and from the flasher (probably a 6 wire turnsignal harness). Then it sends flash to right front and rear, flash to left front and rear. If it worked before and you plugged LED flasher into same place as old flasher and you grounded the LED flasher pigtail wire per instructions, then either you messed with wiring somewhere, new flasher is bad or both front lights connected to same turn signal output wire or connected together. I don't know anything about LED bulbs, flashers..so it could be some special LED related problem I guess. But check the wiring as I describe. Follow and recheck all 6 turn signal wires.

The 6 are:
1. flasher input
2. Brake switch input
3. Left output to left front and to dash indicator
4. Right output to right front and dash indicator
5. Left output to left rear light
6. Right output to right rear light

Your trouble with fronts may have something to do with them being park and turn. Make sure the park circuit is not mixed with turn circuit. Assume you have dual filament bulbs front and back.