Best Way To Check Brake Light Signal For An Electric Brake Controller On A 1997 Ford Explorer

Published 11/04/2016

Question:

What voltage should I be seeing on the light green wire that comes from the stop light switch when the brake pedal is engaged? I have tested both sides of that switch, and have found the switched side Light Green Wire but am only seeing around 0.32v when the brake pedal is engaged. This would be the signal wire used by the red wire on my brake controller. Thanks.

asked by: Josh

Helpful Expert Reply:

When checking the wires associated with a brake controller, you should use a incandescent circuit tester like # PTW2993. This will actually cause a power draw on the wire to light the bulb and give you an accurate visual of if the system is functioning correctly. You will need a 12V power for the brake controller to work.

I can confirm you are testing the correct wires and that the green wire will connect to the red wire on your brake controller. If the incandescent circuit tester is showing the same lack of power, you may have a bad brake switch.

I've attached a couple articles to help.

expert reply by: Jason S