Trailer Brake Controller in 2003 GMC 2500 HD Works on One Trailer But Not the Other

Question:

I have bought all my trailer needs from e-trailer, and Ive been very happy,but Ive got a problem!I have 2003 GMC 2500 HD with the 3015-p connector with a Tekonsha break controller that Ive been using with 12 ft enclosed trailer and it works great. I bought a Kaufman trailer and it will not work unless the controller is in the manual state to activate the breaks ,do I need the 3025-p wire harness to work with that trailer?And will it work for both trailers?Or will I need to change the connectors when using a different trailer?From one to the other?

asked by: Randy H

Expert Reply:

The harness that is used to install a brake controller like the Tekonsha P3 # 90885, like the # 3015-P that you're currently using, is going to be vehicle specific and not trailer specific. The # 3015-P is the correct harness for your 2003 GMC Sierra 2500, so you do have the correct controller adapter plug for your truck.

Usually when the brake controller only controls the brakes with the manual override and not the pedal, it indicates a bad connection with the stop light switch; the fact that this is happening only on one trailer is a bit odd. I would check to make sure that the connection on your harness is in good working order and that there is no damage to any of the wiring.

If you can verify that the wiring on the stop light switch (red wire) is in good working condition, please let me know and I can give you a few other options to check. I've also linked a help article on brake controllers and 7 way wiring so you've got wiring diagrams.

expert reply by: Erik B