Troubleshooting Curt 4-Pole Wiring Harness 55542 on 2009 Toyota Corolla

Question:

I bought a model 55542 trailer wire adapter for my 2009 Toyota Corolla. Install was easy but only the driver side lights are working. So I replaced the trailer lights. Still the same problem I had a friend plug in and the trailer lights worked fine. I bought a second wire harness and still no passenger lights. Car lights work , but not trailer. Can you help?

asked by: Patrick

Expert Reply:

Thank you for purchasing the Curt trailer wiring harness # 55542 and for sharing the detailed troubleshooting steps you have already taken to find the issue with the passenger-side trailer lights. It sounds like you have had a friend connect his vehicle to your trailer and noted that the trailer lights all worked fine with his vehicle and wiring.

Based on this it sounds like the problem is with the harness-to-vehicle connection point on the passenger side.

Disconnect the passenger side connectors and inspect all the electrical contacts inside them on both the vehicle and harness connectors. The issue could be as simple as one or more of those contacts simply not making a solid connection to the mating contact on other connector. Or there might be some foreign material trapped there that blocks the connection.

In this case you would simply apply gentle pressure with a toothpick or small screwdriver (or similar implement) to lift/bend the electrical contact so that it applies stronger pressure on the mating contact or remove the foreign material.

If you happen to have a circuit tester like # PTW2992 you can test the wires leading into the harness module (the wires that bring the vehicle signals into it) when it is connected. If the car's passenger-side light signals are entering the module but are not leaving the module on the 4-pole side then the harness is defective and should be replaced. This Curt product has a 1-year warranty.

expert reply by: Adam R