Curt Spectrum Brake Controller C51170 Is Not Engaging With Brake Pedal

Updated 09/01/2026 | Published 08/27/2026

Products Featured in This Question

Curt Spectrum Trailer Brake Controller - Dash Mounted Knob - Up to 4 Axles - Proportional

(454)

$269.95

Roadmaster Stop Light Switch Kit

(709)

$55.40

Question:

my 51170 applies the brakes when in manual mode but not when I apply the brake pedal. I have tried adjusting it all the way up on output and sensitivity but only the first red led on the left lights up when the pedal is applied.

asked by: Matt L

Expert Reply:

Hi Matt!

You may need the Roadmaster Stop Light Switch Kit # RM-751490. This is pretty common on Jeep Wranglers, but a few other vehicles need to add it as well. Basically, the stop light switch wire on these vehicles isn't useable for brake controllers and an additional stop light switch needs to be added for it to work properly.

That said, what is the year, make, and model of your vehicle? It could be what I mentioned above, but it could also be something else and I want to make sure I'm getting you accurate information.

expert reply by: Lazer S