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rusty duck 08-21-2012 11:53 PM

LED tail light problem
On my '37 Ford coupe I have led taillights and the brake lights and turn signals work on both tail lights until I turn on the headlights. Once the headlight switch comes on the right rear light goes dead, but the left one still works as it should. I thought it was a ground issue on that light, so I disconnected the ground wire to the right tail light, cleaned the metal surface on the frame and reconnected the ground, but nothing changed. I am at a loss. There is no socket to the light so I can't use a regular tail light bulb(1157) to check it with. I always thought an led light either worked or it didn't, any suggestions?

Cape Cod Bob 08-22-2012 07:03 PM

Is this car a newly wired car and you are checking out the lites for the first time?
Since the right rear works without the headlite switch on indicates that the ground is GOOD.
Typically the headlite and taillite circuits are separate from the brake and turn.
I would suspect the switch or wiring . It could be even something as simple as the switch grounding out the right taillite wire when pushed on or causing that wire to be disconnected when the switch is on.
Check how it works with the switch out and dangling. Look for loose wires or bad stacon connections.
Stacon connectors should be crimped twice. Once on the wire and than also crimped to the insulation.That will help keep the wire from flexing and breaking where it enters the stacon.:welcome:

rusty duck 08-23-2012 12:05 AM

LRED Tailight Problem
Thanks for your reply. It is not new wiring, but an excellent wiring kit that has been working well for the two years I have owned the coupe. All wiring looks very good, and neat and tidy installation. The fenders were taken off to have patch panels welded in and then they were repainted. The problem came after the fenders were reinstalled by the shop. The repair shop is at a loss as well. I will try your suggestions.

Supercharged03 08-23-2012 09:09 PM


Originally Posted by rusty duck (Post 1585270)
The problem came after the fenders were reinstalled by the shop.

What would have changed when the fenders were reinstalled?

The ground.

Why not try attaching a direct ground wire from your LED to a GOOD ground on the body and eliminate the reliance on the fender's attachment to the body? You should be able to rig this temporarily for a test.

rusty duck 08-23-2012 09:59 PM

led tail light problem
Thanks for your suggestion. I made a good ground to the frame and the problem persists. I am not convinced the problem is in the headlight switch as one person suggested. I am going to next take the left tail light off and check to see how it compares to the right taillight and go from there.

ogre 08-24-2012 08:55 AM

led lights have polarity, check the connections they may have crossed a wire

rusty duck 08-24-2012 10:55 PM

led taillight problem
Thank you. That will be my next thing to check.

sedanbob 10-18-2012 09:38 PM

I had a similar problem with my front parking/turn signals - had LEDs front and back, and the correct flasher for LEDs. Both left and right worked when the lights were off, or just the parking lights on. When I turned on the headlights, left worked and right didn't - came on steady, no blink. I switched the lights left to right to check if it was the light or the wiring. The right now worked and the left didn't. The circuit within the LED was the problem. I got tired of fighting with it and swapped both front lights out for regular bulb fixtures - no more problem.

rusty duck 10-18-2012 10:07 PM

LED light problem
I solved the problem when I cross checked the wiring on the left tailight and discovered the shop had crossed wires on the right side. I didn't see it at first as the shop had pigtailed the wires of a different color from the ones originally in the wiring kit. Everything works fine now. Thanks for all the suggestions, as in the future they may come in handy.

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