P3 Brake Controller Says No Trailer Connection and Brake/Turn Signals Not Working On Trailer

Question:

Hi , I just installed the P3 and when I first started to test it , it starts up ok but as so as you hit the brake pedal the P3 says the no trailer attached message. Also the camper brake and turn signals dont work. The 4 wire plug at the back of 2011 Sienna works when I run a bypass around the 7 wire plug. What do suggest.

asked by: Phil

Expert Reply:

On the 7-Way trailer connector on your 2011 Toyota Sienna check to make sure the white ground wire is attached to a clean, bare metal surface. A weak or missing ground would cause both of the problems you have described.

It could also be corrosion. The easiest things to check are the vehicle and trailer side connectors. Make sure that each is free of corrosion inside, where the wires attach, and outside on the pins.

expert reply by: Michael H