Troubleshooting Draw-Tite Activator IV Trailer Brake Controller on 1987 GMC Sierra

Published 02/12/2015

Question:

I have a 1987 GMC Sierra 1 tonne. I just recently had my brakes/drums etc changed. The activator 4 which has been on the truck since I bought it for 8 or so years ago shows the digital display but the manual braking does not work, and i am assuming the trailer brakes are also not working , what should I look for? Thanks for your help

asked by: Suzanne

Expert Reply:

You will need to test the brake controller wiring using a circuit tester like # 40376. First check and test the connector at the bumper. Next check the red wire connection. It should be attached to the wire on the stop light switch that only has voltage when the brake pedal is pressed. If your red wire is connected to a wire that carries even a few volts when the brake pedal is not pressed, it is not the correct wire.

Make sure that the white ground wire is attached to a clean metal surface and that it is free of corrosion. Your black power wire should have a constant 12 volts.

If the issue is still not solved, sever the blue wire and test for voltage on the brake controller side of the wire.

If you find a problem, be sure to wire the brake controller correctly and see if that solves the problem. If you still have a problem then the brake controller has gone bad and would have to be replaced as there are no serviceable parts inside the unit.

expert reply by: Chris O