Troubleshooting 4-Pole Trailer Wiring Installation on 1998 Plymouth Grand Voyager

Question:

The turn signals work on the trailer but the brake light and light does not. What could be the problem. Installed this kit on a Plymouth Grand Voyager.

asked by: Wolfgang S

Expert Reply:

The best way to test the lighting functions on your 4-pole harness # 118334 is to disconnect the trailer and apply a circuit tester like # PTW2993 to the connector's pins. You'll need a helper in the Grand Voyager to activate the light functions while you apply the grounded tester to one circuit at a time. The linked video shows how the tester works to tell you when a signal is present.

On your 4-pole wiring setup the brown wire carries running lights (on when your headlights are on) and the green and yellow wires each carry both brake and turn lights.

If the 4-pole connector carries the correct lighting signals when tested in this way, then the issue is likely to be a bad ground on the trailer. Check both the trailer's main ground wire and also the grounds for the individual lights that are not operating. Ground wires must be tightly affixed to a clean bare metal spot on the trailer frame. If the light uses a mounting stud as the ground then this must be able to make direct metal-to-metal contact with the trailer.

If the correct signals are NOT present on the Grand Voyager's connectors then you can unplug the harness from the tail lights to allow you to inspect the contacts inside all the connectors. Look for corrosion, bent pins, trapped foreign material, etc.

You may also care to refer to the linked article on troubleshooting 4-pole trailer wiring installations.

expert reply by: Adam R