Trailer Light Problems, 2500 HD AT4X

[TXDucatiRacer]

After checking out this same issue on a few different forums I haven't seen a true fix or identification of a problem other than maybe the trailer light module. I purchased a new 24 AT4X to replace an 18 Silverado to tow a 23 Grand Design toy hauler with LED lights, rear camera and solar.

When connecting my trailer to the AT4X I continue to get an error where the left turn signal and brake lights do not work. I tried an adapter from Furrion that has resistors built in, to help correct the issue. While more of the lights work (right brake, reverse and right turn) the issue is still present.

Took the truck back to the dealership who initially identified that a trailer light module was bad. Dealer repair paperwork suggests code B1B56 was stored, however that code doesn't appear to correspond with a trailer lamp issue? At any rate, the dealership replaced the trailer lamp module. A trip back to the trailer and the exact same lighting conditions are found. To confirm it is not the trailer, connections to other vehicles (Toyota, Ford, Dodge) were made and the trailer functions as normal, just as it did with the 18 Silverado.

Anyone have some insight as to what this issue may be or what to correct moving forward?

 

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[Viking Truck]

Sorry I can't be of help but I have a question. Do you believe part of the problem is the LED lights on the trailer because the truck is expecting higher current draw of incandescent bulbs? Tried LED taillights in my 2015 and got an error for that reason.

 

[TXDucatiRacer]

It would seem the issue is with the truck not recognizing the trailer. I have hooked the same trailer up to a Toyota, Ford and Dodge, all of which operated the trailer as normal. The hooking up of the trailer to the different vehicles was done without any change to the trailer. Also seems odd that my 18 Silverado also powered the trailer correctly and this 24 GMC isn't. Other forums suggest that the trailer lamp module and or the updated electrical system might be causing some of these issues. But I haven't found anything definitive yet.

 

[Cohaagen]

I have read about multiple trailer hookup issues on various forums. Disheartening. Most of us buying these trucks trailer and this is seemingly a simple thing to get right.

 

[gemarsh]

I'm kinda getting the impression it's the solar. Something with the truck "see's" a higher input from trailer than the truck side and wigs out.

I was also under the impression using a '23 and older trailer light module was curing it.