Troubleshooting Running Lights Not Working On Trailer  

Question:

Expert Reply:

The first thing you want to do is determine if the problem on your running light circuit is on your 2003 Silverado or if it is on your trailer.

The easiest way to do this is to use a circuit tester like our part # PTW2993 and test the circuits while a buddy activates them. Check out the video I attached that shows how to do this.

If there is voltage in all the right places then you know the problem is in your trailer. If there isn't voltage on the running light circuit then the problem is on the vehicle side of the equation. You will need to trace the wiring up from the 4-way on your vehicle and fix any obvious signs of shorting such as cut or exposed wires.

If the problem is on the trailer side you can start by checking for and cleaning out any dirt or corrosion in the trailer side connector. Next, move on to checking the main ground from the plug. It should be attached to a clean and corrosion free bare metal surface on the trailer frame. You can also check to verify that the pin on the trailer side for the tail lights matches up with the pin for running lights on the truck.

Next, you can check the grounds at each of the lights. Trailer lights usually ground through the mounting studs and they should be attached to a clean and corrosion free bare metal surface. If the trailer has extra running lights, it may be too much of a power draw on the system and this could cause the lights not to work. You will need to either remove some clearance lights or replace them with LED versions if this is the case.

I attached an FAQ on 4-way installs for you to check out also.

expert reply by: Jameson C

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