Troubleshooting Trailer Wiring Harness on 1999 Jeep Cherokee  

Question:

Helpful Expert Reply:

If you have tested the 4-pole connector on the # 118376 and found that you have voltage at the running light pin but not at the right turn/brake and left turn/brake pin, you will need to troubleshoot the converter box.

Have a helper sit in the drivers seat so they can activate the various lighting functions. Test each function on the input side of the converter box. With the right turn signal activated, you should show voltage on the green wire entering the box. The same goes with the yellow wire when the left turn signal is turned on. Now check the green and yellow wire on the output side of the converter box (side with the trailer connector). If you have voltage entering, but not leaving the converter box, the box is faulty or has been shorted out and should be replaced.

If there is not voltage entering the converter box, check that the connector that taps into the vehicle wiring is plugged in fully. When plugged in all the way, the connector should click into place.

Before replacing the converter, closely examine the trailer wiring, looking for the short circuit that cause the converter to be fried. Look for pinched or broken wires, and worn or cracked wire insulation that would allow the copper wire to short out on the trailer frame.

I have linked you to an FAQ article and troubleshooting video that should be helpful.

expert reply by: Mike L

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