What Lights On Curt Spectrum Are Supposed to Activate When Pressing Brake Pedal and No Trailer?

Updated 04/23/2026 | Published 03/28/2024

Question:

I had my local chev dealer purchase and install the C51170 controller on my new 2024 Silverado Custom and they indicated that their tech had tested the system for functionality and it passed. After reviewing the operation check list it indicates I should have two green lights glowing when I depress the brake pedal without a trailer connection? Has the dealer missed something when they installed the unit? Want to be safe... thx

asked by: Terrence J

Expert Reply:

I have added a link near the bottom of this page with the instructions for the Curt Spectrum Trailer Brake Controller # C51170. When not connected to a trailer and pressing on the brakes you should see 2 blue lights flash on each side of the control knob. If you can tell me what you are seeing I can help you to determine what fault you may be having.

expert reply by: Bud M

Terrence W.

3/28/2024

Hi Bud, The control head indicates no blue lights or any others with the vehicle running or not when the brake is applied? If I push the knob in the seems to go through other settings including brightness. I have yet to buy a trailer, that was to be next so, I have yet to test its true operation status! I'm trusting the Chev Dealer to have done the install correctly.

Bud M.

3/28/2024

@TerrenceW The controller should be a plug and play install using the Wiring # C51525 so there really isn't much to fail with the setup. You might check your fuses for the factory trailer brake controller wiring and any that deal with the brake switch to ensure one didn't blow after the install was performed.

Terrence W.

3/28/2024

Hi Bud, just left the Chev Dealer and they believe that the fault is in the unit they had ordered? Did show them your opinion and they only asked how I found a Tech? Again, they indicated that the blue lights only come on when the trailer is first disconnected showing the break in continuity. The instructions on the unit show it's a safety feature for the operator and for the light to only come on once for a quick moment during a non- emergency disconnect makes no sense to me. Any opinion is welcome at this point! Thx.

Bud M.

3/29/2024

@TerrenceW If the dealership who ordered the part and installed it says the unit is bad then let them replace it under warranty. If they then determine that it was not the unit then they are still going to have to fix it for you.

4/23/2026

Hi Bud, I hope you don't mind another issue question with the c51170 bc. A pro truck shop installed mind in 2023 in a 2018 Highlander. It new to me at the time. Ever since an occasionally and months apart i have had dead battery, happened at least three times, and now on the third battery. I took it to my regular mechanic after battery 2(AAA road service April25) failed. He tested it and couldn't find a problem, but recommended a better interstate battery. Now April26 and another sudden dead battery. Recharged it and again seems OK. But of course, the problem is not solved. Any ideas? My research (batteryskills.com)indicates bc parasitic power leaks occur from this bc. I have an appointment for it with the original installer next week. Any insight beforehand is appreciated. My best PJ