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Posted (edited)

Don't know on 3500 but when I was having problems with mine they said its all located under rear bed spare tire.

 

 

Edited by elcamino
Posted

Did you see this in the Q & A section?

 

GM part number 23114650 replaces 23104453. However, both part numbers have been updated and replaced. The current part number that a GM dealer would recommend is 23337305.

  • Like 1
Posted
4 minutes ago, NYRESCUE said:

I checked but didn't see anything when I dropped the tire.

You sure the truck has this feature?  Cannot be added.

Posted

Should be a bracket, left rear of the frame.  If you drop the spare, assuming its a pickup, you should see a module on a bracket.  The trailer brake control module is on top of the bracket. 

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Posted (edited)

OK, I found it..yep its on top of another module when you drop the tire. Thanks!  I replaced it with the part I listed above, not knowing there was a new version. Is this still ok or will I still get the disconnected message with this version?

Edited by NYRESCUE
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  • 5 years later...
Posted

Hey all. I have a 2015 3500HD with the trailer brake message. I am told by the dealer that there are two modules that look exactly alike, but only one is for the trailer brake controller. I found one of them, thinking it was the correct one, and replaced the module, but this did not fix the issue. This truck has a service body, and a second gas tank where the spare tire would typically go. Dealer states that the second module should be above the spare tire location where the additional fuel tank is now located. I looked above the tank as best I could, but could not locate the other module. Can anyone tell me where it could be located? The one I replaced was easy to find. It was on the front of the rear fuel tank, next to the fuel pump control module. As for module I'm looking for, can anyone give me some insight?

Posted (edited)
21 minutes ago, dougefish said:

Hey all. I have a 2015 3500HD with the trailer brake message. I am told by the dealer that there are two modules that look exactly alike, but only one is for the trailer brake controller. I found one of them, thinking it was the correct one, and replaced the module, but this did not fix the issue. This truck has a service body, and a second gas tank where the spare tire would typically go. Dealer states that the second module should be above the spare tire location where the additional fuel tank is now located. I looked above the tank as best I could, but could not locate the other module. Can anyone tell me where it could be located? The one I replaced was easy to find. It was on the front of the rear fuel tank, next to the fuel pump control module. As for module I'm looking for, can anyone give me some insight?

 

 

Sounds like you have a 3500HD chassis cab so the dealer would be incorrect in their explanation.  Pickup trucks or box delete pickups which would use the regular boxed frame, the modules would be above the spare on a bracket. 

 

 

Chassis cab so the big open C channel rear frame rail trucks, its different.  See below.   

 

Trailer brake is operated via the chassis control module (the big guy), the trailer brake power control module (the little guy), and then the trailer brake control switch in the dash.  The switch in the dash is a common failure point too, so don't rule that out.  The system does set codes which have diagnostic trees to follow as well.  

 

 

chassiscab.png.159160d2a023369a751c57d8af9634dc.png

Edited by newdude
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