Why Are My Trailer Running Lights Not Working?

Question:

I did not have continuity on the running lights for the first time in 19 years since we installed the lights always had lights in the past and had not done anything to disturb. I ran a new split cable to both sides of the trailer and still no continuity. When I jumper the running lights using the turn signal wire, the lights running lights work and come on. I thought there might be a problem with the running lights module in the truck so I have purchased a new one but am hesitant try it as if there is a problem with the trailer lights themselves, I do not want to blow it up, Likewise when installing the new wiring harness, we tried to check continuity by first disconnecting the right side and checking for continuity and then doing the same on the left with no continuity in either case. Am stymied Please help. Thanks

asked by: TOM R

Expert Reply:

The first thing to do is get a voltage reader like circuit tester # PTW2993 and test the running lights pin while the running lights are on. If you are not getting voltage there, we know that the problem is with the wiring of the truck. If you do get voltage there, then we know that the issue is with the trailer.

For the vehicle, I recommend checking for frayed wires or any fuses (which can be found in the owner's manual). As far as the trailer, I recommend tracing the wiring and making sure there are no damage in the wires or in the 7-way or 4-way connector. Also, there might be some debris or dirt within the pins of the connectors.

expert reply by: Bob C