Why Does My GMC Sierra Show Check Trailer Lamp Warning with LED Lights on My 5th Wheel?

Updated 05/17/2026 | Published 05/11/2026

Question:

I have a 2026 GMC Sierra 3500 HD Denali towing a Cedar Creek 5th Wheel with LED lights and Haloview camera system. The lights on the RV work however I keep getting intermittent Check Trailer Lamp warnings. Could the C57003 help with this?

asked by: David T

Expert Reply:

Hello David,

Thanks for writing in!

Yes, the # C57003 adapter will fix the issue you’re seeing. Your 2026 GMC Sierra’s trailer light monitoring system is designed to look for a certain level of power draw to confirm the trailer lights are working. Since your Cedar Creek 5th wheel has LED lights, they draw much less power than traditional incandescent bulbs, which can cause the truck to think there’s a problem even when everything is functioning properly. That’s what triggers those intermittent “Check Trailer Lamp” warnings.

The # C57003 solves this by adding a small amount of load to the lighting circuits so your truck can properly detect the trailer. Once that load is present, the system recognizes the lights correctly and the warning message goes away while everything continues to work as it should.

It’s still worth taking a quick look at your connection just to be thorough. Make sure the 7-way plug is fully seated and clean, and check that none of the pins are bent or corroded. Since you’re also running a Haloview camera system, you’ll want to confirm that wiring is cleanly integrated as well so everything is getting a consistent signal.

If everything looks good, the # C57003 is a simple plug-and-play fix that directly addresses what you’re experiencing with LED trailer lights on a newer GM truck.

What adventure are you looking most forward to this summer? Where are you going and what are you most excited to see?

expert reply by: Kate F

Adapter Installed
(click to enlarge)

Greg D.

5/13/2026

worked for me, my sprinter based view wouldn't react properly with towed bronco .. with the adapter ...it does.. grd

Kate F.

5/15/2026

@GregD Thanks for the response Greg =)

Richard

5/13/2026

I’ve used the adapter since last October on my2024 F250 and Rockwood travel trailer after I had LED lights added to the back corners. I added them to ensure people following us while I had the bikes mounted on the rear of the trailer could see our braking and turn signals. Without the adapter the lights were intermittent at best and the truck screen indicated trailer lights problem. I did not have the problem prior to adding the additional LED lights.

Kate F.

5/15/2026

@Richard Glad to hear this was the solution to get your lights working correctly Richard, thanks for the response!

Brent

5/13/2026

Hi David, It did not help with the trailer lights messages, (truck control module replacement fixed it-2025 high country Silverado). However, I was getting intermittent "trailer brake disconnected - brakes disabled" messages. I no longer get those messages using the adaptor. Brent