Need to Locate Stoplight Switch Circ. on 2014 Chevrolet Express Van When Installing Brake Controller

Updated 04/28/2014 | Published 04/25/2014

Question:

Im installing a trailer brake controller in a 2014 Chevy Express 3500 w/o the factory wiring harness, and need to tap into the stoplight circuit so the brakes will trigger the controller. Some sources said to tap into the harness at the BCM, light-blue/white wire on the brown connector. However that wire is very light gauge, and shows 0.4 volts when brakes are released, not zero. Might do strange things with the controller. One source recommended tapping into the CHMSL 3rd brake light circuit, which is light blue and eventually goes to the BCM. Tested circuit at bulbs, it goes to zero when pedal is released. Does anyone have a diagram? Lots of wires going into BCM, just wondering which plug I should be looking at for the CHMSL circuit. Thanks!!

asked by: Greg B

Helpful Expert Reply:

I would recommend the CHMSL circuit for tapping into just the brake light signal of your 2014 Chevy Express Van to install a Prodigy P3 Brake Controller part # 90195 in your 2014 Chevy Express Van.

This circuit will only see voltage when the brake are applied and should work very well as this is an often used circuit for brake controller installations.

I also attached an FAQ on installing a brake controller from scratch for you to check out.

expert reply by: Jameson C