LED troubles.

Bad ground?? I would check the ground first

 

LEDS are usually one-way only. Do you have them wired correctly?

 

If I recall correctly they have a Black and White wire. Black goes to the Hot and the white to Ground.

 

LED lights are one way, so basically you are not allowing any current to flow from the "+" to the "-". We will not get into the Diode versus a Zener Diode.

The mistake most will make that they will see the Black as being Ground. Black is always a Hot even in your house wiring. Black should always go to the Breakers. If you run the white to your breakers the device plugged in will be first in line on any power surges and the circuit breaker is last. Black to Brass to a good saying to use with wiring outlets.

LED Lights with 2 wires are generally going to be a single function light. This means marker light, running light, brake light or blinker. In this case one of the wires will be ground (-) and the other is positive(+). Generally a white and a black wire will be provided. The white will normally be the ground(-) and the black will be the positive(+).

https://www.12volt-travel.com/knowledgebase/led-lights-wiring/

 

A couple things

First off there are yellow or amber lights on the market that are intended to be blinker lights they first light up all the way and then turn off if it is on too long. I have no clue why but I bought a couple of these a while ago from a pilot and they were great for turn signals but if tested they would turn on and then turn off.

Second is that there are a number of cheap and rather worthless lights on the market including those at the truck stop. We bought a bunch for a couple new trucks to convert and they burned out within a month, the drivers always have their lights on when the truck is moving. These were replaced by lights from signal-sta and have yet to fail

Third is wiring, I hate this idea of using black, it is the hot side in electrical work and is really confusing, so if you want to actually do something right to make things look professional, use instead of black try yellow for the ground, and red for positive. I know some of you think this is silly but I've been working on some of these trucks for radio/CB issues and it drives me up a wall to see black wire used in both the inverter power lines and the DC power lines.

And fourth just a little FYI, do not be fooled by the dot approved crap that is advertised. No light is approved by the dot for any road application. The compliance is done by self-declaration with a standard system for that declaration. Some of these lights they sell at places like Iowa 80 are pure crap and are not compliant at all, even though they claim it is. Buy products from one of the few really good companies out there like signal-stat or truck lite,

Here is my suggestion - by one good light unit that is made by a company you can trust, like truck lite and first test it, then put in the place of the other light to see what's what. It can tell you quicker than anything else if it the light or the wiring.

 

They can take a 9v battery to test the light.