No Trailer Brakes When Stepping On Brake Pedal in 2003 Hummer H2 with P3 Brake Controller

Updated 03/11/2016 | Published 03/10/2016

Question:

I had this installed in a 2003 Hummer H2 and it brakes if I use the manual switch but does nothing when I apply the breaks. I have no error message and see nothing wrong when I run the TS

asked by: Bryan

Helpful Expert Reply:

Your 2003 Hummer H2 has the same setup as the GM SUVs and trucks of the same year. You should be using brake controller harness # 3015-P. Make sure that the position of the red wire in the end of he harness that plugs into your H2 is positioned in the top right corner (with the connector clip facing up) next to the blue wire. If it is not in this location move it there. This is the wire that tells the controller that you are stepping on the brake pedal.

If the red wire is in the right place then the likely cause is blown stop light or CHMSL fuse and replacing it will fix the problem.

expert reply by: Michael H