Question Was Asked By - Scott T

Troubleshooting T-One Vehicle Wiring Harness # 118428 on a 2007 Jeep Patriot

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Question:

When I am done connecting all the contactor. I test all the wiring and blinkers and Brake lights work on both sides. When I turn the headlights on there is no lights on the trailer until I press the brakes down once then the lights are on the trailer. Is this done on purpose to conserve power or is there something wrong with this unit. This is my second unit in two years. My first one failed after two years and I recently bought and but in the new one. Please let me know if there is something wrong or is this the way it works. thanks

asked by: Scott T

Expert Reply:

It sounds like you have a bad ground somewhere. When you turn on the headlights the maximum amperage draw is on the trailer connector and this causes marginal ground connections to show up. I would start by checking the ground connection on the wiring harness on the vehicle.

Make sure that it is grounded to a good clean point and that the screw is tight and not stripped out. If the ground is good use a circuit tester, item # 3808 if needed, and check the trailer connector, with the trailer not hooked up. If the wiring harness is working properly, lights on and off, then the problem is the trailer. If the wiring harness is not working properly then you will need to check the inputs into the converter box. If all connections into the converter are working properly then the converter is bad and will need to be replaced. If all connections are not working correctly, check the connections to the vehicle wiring and make sure they are securely connected.

If you find it is the trailer you will need to check all of the ground connections especially where the taillights are mounted to the trailer frame, and where the light brackets are mounted if they are bolted to the frame. If a plastic license plate holder is mounted between the left side taillight and the trailer frame this could be the problem. Once you have all of ground connections checked, if the problem persists, you will need to check for a broken pinched or frayed wire on the trailer somewhere.

expert reply by: Bob G

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