Troubleshooting Trailer Wiring Harness 118460 on 2010 Toyota Matrix

Question:

On my Toyota matrix 2010 if the parking lights are on and if i step on the brakes the parking lights go very dim. What could be the problem?

asked by: Normand S

Expert Reply:

The wiring harness # 118460 that you referenced is a correct fit for your 2010 Toyota Matrix and it sounds like your trailer's clearance lights are dimming when you press the brake pedal. When this happens the cause is often a weak ground connection which is easy to correct.

What you can do is disconnect the white ground wire's ring terminal from the grounding point. Sand and clean that spot so that you have exposed clean bare metal that is free of paint, primer, undercoat, rust and grease. Then apply protective dielectric grease like # 11755 and securely re-attach the ring terminal to that clean grounding point. You can repeat this same process on the trailer wiring by disconnecting, cleaning and re-attaching the trailer ground in the same way.

You can also refer to the linked article on troubleshooting wiring installations.

expert reply by: Adam R