Trailer Wiring Error

maizeblue28 · April 13, 2021

Hi, I have a 2019 Sierra 1500 SLT and I've been having frustrating problems with pulling a trailer for 2yrs now. When I first bought the truck my drivers side blinker didn't work on my trailer which worked on my old truck and the trailer is only a few years old. I was finally able to convince the dealer it was the truck and they replaced the trailering module and that fixed the problem. I still have an issue though. I get random check trailer wiring messages. Sometimes it's every 10 seconds, sometimes it's every 30min. I have it narrowed down I believe to the brakes because it seems to happen more often when I apply the brakes and when I let off I get the error. I also will get random "trailer brakes detected" messages when driving and sometimes a trailer brake gain not recalled message. To troubleshoot it I disconnected the trailer brake wire inside of the 7 pin connector and the errors completely go away so that is why I think it's related to the trailer brakes. I've put on 2 brand new 7 pin connectors with no changes. All the wiring connections on the trailer look good and I have good ground on the trailer. So I guess my question is, is this a normal thing that I just have to deal with? It literally drives me insane when on long trips. I don't want to completely redo the brake wiring if it's a common problem. If that will do the trick i'm fine doing it, just don't want to spend that time to do it if it will keep doing the same thing. My trailer lights also blink every 10secs which i've read on here is normal so I don't know if this is normal too. The trailer is a NEO all aluminum 7x14 enclosed trailer with LED lighting.

jnissen · April 14, 2021

Likely the LED lighting and not enough load for the module to properly see it as attached. They may have a software update to correct for that. I think it was part of some security system that would detect if the trailer were attached or removed. You could try some standard light bulbs but that defeats the whole use of the LED's!

maizeblue28 · April 14, 2021

8 hours ago, jnissen said:

Likely the LED lighting and not enough load for the module to properly see it as attached. They may have a software update to correct for that. I think it was part of some security system that would detect if the trailer were attached or removed. You could try some standard light bulbs but that defeats the whole use of the LED's!

Yes, I think that is the blinking issue which I have reluctantly learned to live with. It's the check trailer wiring alert that I can't deal with and I'm asking to see if that is an issue related to how the truck detects the brakes or something or if I have a true wiring issue. I just don't want to rewire the trailer brakes for no reason. The brakes function fine, it's just the error messages I get.

Anacortes Army Guy · April 14, 2021

I'd recommend you hook your truck up to another trailer if a friend/neighbor has one to see if the problem replicates itself. That would at least tell you it's a TV issue or a trailer issue. I pull a travel trailer with full LEDs and have zero issues. And you are correct, the pulsing of the lights every ten seconds or so is normal as the trailer detection feature "checks" to see if you still have a trailer back there, though it's a little weird to see that for the first time as you're walking back out to your rig in the Walmart parking lot and see that from a distance.

Alton Johnson · July 28, 2023

I have a 2023 GMC Sierra AT4. I go through the checklist and do the trailer light test and everything is working but I get a warning. Chect Trailer Wiring. and it will not clear. I have checked the brakes on my trailer and the wiring and everything else is good. Could it be the 7 pin connector going bad or not getting a good connection? Everything works but the warning is driving me nuts.