Should Manual Override of Brake Controller Light Up Vehicle Stoplights

Updated 09/08/2025 | Published 06/14/2025

Question:

Primus IQ brake control on traverse 2016. Stop lights OK when pedal pressed, but when slider bar is pressed no stop lights. Checked red wire on controller and 12v power when pedal pressed and when slider bar pressed. Not sure Why slider bar not lighting up the stop lights when pressed. Thank you.

asked by: William D

Expert Reply:

Hey William, that's a vehicle issue. The controller is attempting to backfeed 12 volts onto the stoplight circuit so that the lights will come on but there is most likely a one way diode on that circuit on the vehicle side which is preventing it from being able to do so. I wouldn't worry too much about it though as this is somewhat common.

expert reply by: Jameson C

Jameson C.

9/8/2025

Hey William, did you find a way to address the issue with the slider bar not lighting up the stop lights? I'm asking because understanding your solution could help others facing a similar situation with their brake controllers.