Troubleshooting a Malfunction T-One Harness on a 2005 Jeep Grand Cherokee

Question:

I purchased this part last year and it never really worked right. I guess I should have contacted you then and had it replaced. The passenger side light has never worked and now the only thing working is the driver side brake light and it stays on constant from the time you turn the lights on. I do not have any problems with the lights on my vehicle. They work fine. I have checked all the connections and everything is properly connected and seems to have a good connection. Im sure my ground is good, if it were not I wouldnt get anything at all. Any solution to my problem without suggesting I spend another 50 bucks? Any help would be appreciated.

asked by: Bryan L

Expert Reply:

It is possible with a bad ground to get some signal. If it was not grounded at all, then you would get nothing, but a loose, or corroded ground connection could result in intermittent or irregular function.

Make sure there is no corrosion built up around the ground. Make sure it has good metal to metal contact. Even a bit of paint can insulate the connection. If the ground is clean and has good metal to metal contact, then you will need to determine if the problem is the converter or in the wiring.

Take a circuit tester like part # PTW2993 and check the wires on the input side of the box. Red should activate with the brake pedal. Yellow is left turn, green is right turn and brown will be come active with head lights. If these functions do not appear as they should, then there is a problem with the vehicle wiring or the connectors for the harness.

If these functions do check out, then you need to check the output wires just on the other side of the box. If these functions work right, then the problem is on the trailer. If they do not function properly, then the box is bad and the harness should be replaced.

If you determine the problem is on the trailer, trace trailer wires and check ground connections for the lights on the trailer.

expert reply by: Patrick B