Troubleshooting Trailer Brake Light Issue with Curt Wiring Kit on a 2010 Toyota Sienna

Question:

Tow car is a 2010 Toyota Sienna. Curt 55580 wiring harness was used by a pro installer in 2011. I have a wiring problem with small utility trailer lights. Running lights work OK. Left and right turn signals work. Brake lights - both come on, but one goes out almost immediately. 4-way flashers - both come on, but one goes out after one or two flashes. Is there a booster or amp that may have pooped out on the car side?

asked by: Dave D

Expert Reply:

Thanks for the information, Dave!

The trouble you're experiencing with the Curt T-Connector # C55580 on your 2010 Toyota Sienna could either be on your trailer directly, or it could be that the converter box has gone out. The best way to figure out which part is the problem is to hook your trailer up to a different vehicle or use a circuit tester # PTW2993 to test the output side of the black box on the Curt wiring.

If the trailer side is the problem then you probably have a bad connection somewhere or a poor ground. If the vehicle side is the problem then it sounds like you need to replace the wiring kit as it's gone bad.

expert reply by: Jon G