I have a 2002 GMC Sonoma. My rear running lights do not work. I've checked the fuse box on the left end of the dash, fuses look fine. Mechanic replaced bulbs, confirmed that there is current going to the back of the truck, but the wires appear to go through a brown female connector above the spare tire, and there is no current going to the tail lights. Is there supposed to be some kind of cap on this connector (which I'm guessing is there to connect to trailer wiring) that acts as jumper to send current to the rear running lights? All other lights on the truck work, with the possible exception of the license plate lights, which just realized I didn't check.
Hello, I'm Cam. Please include all the details about your issue so I can accurately advise you. I cannot see your vehicle so please be detailed.Do you have a trailer plug attached?
I think there is. The wiring under the truck appears to be the original factory wiring. Above the spare tire the brown wiring from the front of truck goes to a female connector, from the back of which more brown wires go to the tail lights. According to the mechanic who checked the wiring, there is current to this connector, but no current past it. The female connector is about 1/4" tall and 1" wide. The inside of this connector is very clean, no dust or dirt. Is there some kind of removable dust cap that belongs there that also acts as a jumper that is supposed to be there? I'm assuming this female connector is for trailer wiring.
Are both right and left out? These should have a separate line for each side, a brown for one and a brown with a white stripe for the other. Do both have power? As for the lights and junction at the back, there is a junction pack that looks like a connector with a cap that splits the wiring to the lights and license bulbs.
Yes, both bulbs are out. As I understood the mechanic that looked at my truck there is no power at either bulb. If what I have called a connector is the junction pack, there is no cap on it. You can look inside it and see the contacts. Could a missing cap for the junction pack be the problem? Or do you see something else?
That could be. What are the wire colours in it?
I remember being shown all brown wires attached to the back of the junction pack, and seeing narrow white lines on the side of some of the wires. I think I saw a total of 8 wires. I couldn't say for sure how many wires had the white stripe, but I would guess no more than half the total at most. Would there be a junction pack in the front end that I could borrow the cap from and test in this one? If so, where would it be found?
There would not be, so if they Are the same color then simply splice the browns together and the brown and white stripes together to correct this issue.
Last questions, I think. What is the purpose of the junction pack? Or put another way, why does GMC put a junction pack in the factory wiring harness? Will removing it cause any complications later in installing wiring for a trailer?
The pack is put in to splice the wires in a clean way, removing it and manually splicing the wires will be just fine and cause no issues.
GM Grand Master Technician 2007. 11 years experience.