Troubleshooting ABS Dash Light When Using Brake Controller on 1999 Ford F-250

Question:

hooked controller wire to brake switch wire RED/BROWN workedbefore hooking to trailer now my ABS light comes on on the dash what wire on the switch should it be hooked to 1999 f250sd

asked by: Ron

Expert Reply:

When hardwiring in a brake controller you need to attach the brake controller's red wire to the cold side of the brake light switch. There are sometimes several wires that go to the brake switch and sometimes a few coming out of it as well. You need the one that only shows power when you step on the brake pedal and not at any other time. I don't have the wiring diagram for color coding on your 1999 Ford F-250 Super Duty truck, so I can't give you that information.

You can use a circuit tester such as # PTW2993 to test the wires and make sure you are connected to the one that only has power when the brake pedal is pressed. If connected to the wrong wire, the controller can send power down the red wire (depending on the controller) to illuminate the vehicle brake lights when the manual override is used and this could be causing the ABS light to come on.

expert reply by: Jason S