Trailer Light Issue

[Dreshajg]

Hello all. I’m currently having an issue with my left tail light on my boat trailer.

When the vehicle is in the “RUN” position but the engine is off the tail light works fine. When I start the vehicle and have the engine running the left taillight on the trailer does not work.

I’m not sure if this a vehicle or trailer side wiring issue. I’ve already checked the fuses and they are fine, and have tested the voltage to each pin which is fine as well. I’m truly lost as to what to do.

 

[n8zcc]

At first glance, it sounds like a grounding issue. The presence of voltage means the circuit is intact, but it is not an indicator that current can flow. Start checking all ground connections, starting with the left trailer light.

 

[Dreshajg]

At first glance, it sounds like a grounding issue. The presence of voltage means the circuit is intact, but it is not an indicator that current can flow. Start checking all ground connections, starting with the left trailer light.

Do you think it’s trailer or truck side that could be the issue?

 

[n8zcc]

Do you think it’s trailer or truck side that could be the issue?

I don't have the information on your issue to make a judgment.