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2006 Jeep Grand Cherokee - Help with hitch wires

I have a 2006 GC Loredo fitted with Tow bar. LH rear tail light does not work and when plugged into the vehicle the tail lights on my trailer do not work. Help please.

Are you handy with a digital volt meter (DVM)?? If so, follow along, if not take the Jeep to a trailer specialty store. they can diagnose and fix this.

First fix the LH tail light. It is either a bulb or a ground. Use the DVM to determine you have both. You’ll need a helper to press the brake pedal and turn the lights on and off. Once that is fixed, check the trailer again. does it work? Great. No? Probe the Jeeps trailer connector. The wiring diagram is below and shows the rear of both the Jeep and the BACK of the trailer’s connector, not the part that goes into the Jeep first.


If the Jeep is OK, which I expect it is, test for continuity and grounds in the trailer’s wiring. I will almost guarantee there is a bad ground and likely a broken wire or 2. It may even be wired incorrectly - wrong wire in the wrong place. Trailer wiring is really poor even on expensive trailers. Fix whatever is wrong.


Trailer lights come and go, it can be ground wire, any wire, light itself, bulb or connection. Parts are cheap at least, but an tvm checking for volts to find the failure is the best.

Under the hood fuse box, Check fuses # 8 and # 9

Debug one step at a time. As an experiment, don’t connect the connectors directly together. Instead start with just two wires, one ground, and say the running lights. Figure out a way to bridge just those two pins, connector pin to connector socket. Do both tail lights now light up on the trailer when they are both lit on your Jeep? etc etc … until you get them all working.