Trailer Lights Working Intermittently when Connected to a 2002 Toyota Sequoia

Question:

Im using an 02 Sequoia as my tow vehicle and had the Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector # C55246 installed. This, however, did not result in the pop-up trailer lights working. The trailer wiring was all tested as receiving power, and ground on trailer is secure. While towing, pop up the lights work briefly, but then go out again. Weve inspected wires and cannot see any signs of damage to any visible wiring. How would I go about testing for a short? Would it be easier to disconnect and bypass existing wiring and rewire?

asked by: Dolores C

Helpful Expert Reply:

Since the trailer wiring harness on your 2002 Toyota Sequoia is working properly the issue must be on the trailer. There are multiple grounds for trailer lights so it could still be a ground issue. The lights working intermittently suggests a ground issue, corroded connector, or break in the wiring, but not really a short. Make sure the trailer side connector is clean and free of corrosion inside, if applicable, and outside on the pins.

The main trailer connector ground and the grounds for all of the lights should be attached to clean and corrosion free bare metal surfaces. Some trailer lights ground through the mounting hardware so that will need to be checked as well.

A break in a wire could occur with little or no evidence on the outer insulation. If you use a circuit tester such as # PTW2993 and have the trailer connected you should be able to test the wiring from the front working your way back on the trailer. Any dead spot would indicate a break in the wiring forward of the dead spot.

On some trailers the wiring can be hard to access because it is routed through the frame or the body. In these cases it would be easier to route new wiring than to try to test the wiring that is difficult to access.

For bonded 4-Wire I recommend # 16-4B-1 which is sold by the foot. If you need 7-Wire then I recommend # DW04914-1 which is also sold by the foot.