Troubleshooting TowReady T-One Vehicle Wiring Harness # 118482 in 2012 Toyota Venza

Question:

I installed the 118482 trailer wiring harness in 2011 and it has worked until now. Just recently when I apply the brakes the right turn indicator lights up. I checked all the bulbs and fuses, all working. Can you tell me how to repair/replace the module?

asked by: Victor G

Expert Reply:

The module in the TowReady T-One Vehicle Wiring Harness # 118482 is not user-serviceable, but you can do a few simple tests to narrow down the possible causes for the malfunction. First, check that the trailer connector itself is free of corrosion. Corrosion does not always have to appear severe like rust but could still cause two circuits to be bridged together; this could cause one light function to interfere with another.

If the trailer connector looks okay, then you can test the wires going into the module to confirm that the correct signals are going in when you activate the vehicle lighting functions. Apply a circuit tester like # PTW2993 to the wires on the input side of the box, one at a time while a helper activates the brakes, lights and signals. If the correct signals are going in but not coming out, then the module is bad, and the entire harness needs to be replaced.

A helpful article with troubleshooting guidance is linked for your reference.

If the module is bad, you will want to check your trailer to ensure there are no shorts in the wiring that might have caused the issue and correct these before installing a new harness.

expert reply by: Adam R