Trailer Tail Lights Come On for a Few Seconds then Shut Off with a 1996 Jeep Grand Cherokee

Updated 01/07/2013 | Published 01/06/2013

Products Featured in This Question

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(126)

$58.32

Cordless Circuit Tester

(15)

$19.27

Question:

I hooked up the box and the tail lights come on for a few seconds and go off. What do I need to do to fix this problem?

asked by: Jerry R

Expert Reply:

There could be a few reasons why this is happening. The first thing I want you to do is go ahead and disconnect the trailer. Then use a circuit tester, like # PTW2979 if needed, to test the wires leading into the converter box for harness # 118349. Run through all the functions of the vehicle (left/right turn signals, brake lights, and running lights) while testing the wires.

If the signals are not correct going in there that indicates a problem with the vehicle wiring that will need to be addressed. If the signals are correct going in, the next step is to test the wires coming out of the converter. If the signals are not correct coming out then there is a problem inside the converter and it will need to be replaced. If the signals are correct then the issue is on the trailer and not the vehicle.

On the trailer side, the problem could be one of two things in most cases. It could either be a ground problem or the lights on the trailer draw more power than the converter is rated for (4 amps stop/turn and 4 amp tail lights). For the grounds you will want to check the main trailer connector ground, the grounds for all of the lights, and even make sure the converter box on the vehicle are all grounded to clean and corrosion free bare metal surfaces.

To determine if the trailer is drawing too much power you will need to look at the light draw of each running light. The ratings should be on the light housings. If the total is greater than 4 amps then you know you are pulling too much power. Switching to LEDs would be the way to go for this problem.

expert reply by: Michael H