Troubleshooting Trailer Wiring on 2004 Chrysler Pacifica

Question:

i purchased wiring harness thru you all 4 wire flat that plugged into existing drivers side rear tail light wiring, till this spring worked now have no lights on trailer but have power at light recpt with meter can take bulb out and have power at recpt. Checked ground on trailer and cleaned still no luck do not have trailer on hitch does this matter or how can I get different ground. I know white is ground should I skin white wire on vehicle side and try to get better ground on vehicle side or how can I run separate ground to check. Stated have power at light but bulb will not light markers lights or any.

asked by: Terry

Expert Reply:

The easiest way to test your 4-pole wiring on the trailer side is to directly apply 12V power from a battery like the one in your vehicle or a charged spare if you have one.

This can be done easily with a set of jumper cables like # HMBC0825 and two short lengths of wire. Connect the negative cable clamp to one piece of wire and the positive to the other. Apply the negative wire to the trailer connector ground pin and then attach the other end of the cables to the battery terminals. Now apply the + wire to each of the other pins on the 4-pole, one at a time. You can refer to the linked photo for the function carried on each pin.

If these work normally then you know the issue is on the vehicle side and checking the ground wire on the vehicle is the first thing to do, just as you stated. Remove it from its attachment point and sand that spot to expose clean bare metal. You can also sand the ring terminal to remove any corrosion. Apply dielectric grease like # 11755 to protect the new clean ground.

You should not need to have the trailer hitched to get the trailer lights to work, but if this does activate them then you know the issue is on the vehicle ground.

expert reply by: Adam R