Trailer Running Lights Not Working Behind a 2003 GMC Sierra
Question:
I have a 2003 GMC Silverado when trailer is connected all the turn signals work but the running light DO NOT WHY????
asked by: Cynthia
Expert Reply:
The first thing to do is check the under-hood power distribution box. This box contains the fuses that manage your towing circuits. Please refer to your vehicle owner manual for individual fuse location. If the fuses are OK, then you will have to narrow down the problem to the trailer or the tow vehicle.
Use a circuit tester, like part # PTW2993, and check each pin on your trailer connector while the corresponding function is activated. When you test the pin that connects to the brown trailer wire, you should get a signal. If you do, then the problem is on your trailer (most likely scenario) and you will have to trace that wire back looking for loose or corroded connections, and broken wires. Also examine your trailer connector, making sure that the pins and sockets don't show any corrosion that would prevent a good connection.
