*HELP* Integrated Trailer Brakes 2011 GMC Yukon Denali *HELP*

[Matthew Snyder]

Hello everyone I am new to the site did some scavenging and found very useful information however have yet to find something pertaining to my exact situation so I hope this hasn't already been answered, if so I apologize.

I have the factory integrated trailer brake on my 2011 GMC Yukon Denali with the Tow Package. After a brief investigation I have found the following..

I have no DIC for gain adjustment when pressing + or - on the controller itself when connected to a trailer or not, after connecting to a trailer the DIC doesn't display "Trailer Connected" message, the fuses are good and installed (30a and 40a), I found one wire taped up and not connected beneath master brake cylinder under hood (it's my understanding this is to be run to Stud #2 on fuse box to apply 12v signal to trailer aux battery), I found another wire taped up and not connected to anything on driver side of fuse box (it's my understanding this is the power signal to the controller itself to be ran to Stud #1) there is currently a wire connected to Stud #1 on fuse block, all three wires in question are red with black stripe, both stud #1 & 2 have ~12v+ on on them. When I connect wires as I believed them to be connected I was able to get 12v between 1 o'clock (+) and 7 o'clock (-) pins on male trailer plug at bumper. Without connecting wires as described there was no signal on these pins. The lights have all been operational no problem. Going from 5 o'clock pin (brake signal) to 7 o'clock pin (-) I get a pulsating 3.5v to 0v.. (it's my understanding this is the module looking for a trailer to be connected), is this too high of a voltage? How much resistance is this looking for I have about 2 ohms on the trailer brake circuit with a tandem axle electric brake system.

Does anyone know the required resistance for the truck to 'sense' a trailer so I could "mock" a connection with a resistor? Should I see some info on the DIC when pressing + or - on controller without a trailer connected? Does this seem like it could be the relay located beneath the spare tire on the truck, or perhaps the module? Maybe the controller in the dash itself? Have any of you experienced this before? What types of readings should I be seeing on the back side of the controller in the dash? Should the wires under the hood be connected in the fashion I described or am I missing something? I understand I should have some voltage at trailer brake pin that is how the truck recognized it's connected but 3.5v seems very high for that.. any assistance would be greatly appreciated.. I would think that the truck had never had the power wires connected under the hood I am left to believe this has never been used before therefore wouldn't understand why it shouldn't function now (aside from corrosion and poor connection) However I am not looking to dump hundreds of dollars into this to keep the ITBC I just think it would be nice over switching to an aftermarket on and skipping the hassle. I have been into the dealer and without turning it over to them which could be thousands in simply labor alone I am hoping to repair this myself otherwise will be installing aftermarket before our 3600 mile travel trailer towing journey and giving up with attempting to restore to its factory glory as I did with the autoride system.

 

[thompsoj22]

someone else hopefully will answer but have the trailer brakes functioned correctly prior to connecting it to your denali? Are the vehicle/trailer connections made without an adapter? There is no reference signal from the trailer brakes to the vehicle, the trailer ground is "extremely important" is it good? are you sure the lugs are terminated correctly at the fuse box? i seem to remember when i hooked up our prodigy the wires allthough only two had confusing attachment info in the book. It's somthing simple.

 

[swathdiver]

Hello everyone I am new to the site did some scavenging and found very useful information however have yet to find something pertaining to my exact situation so I hope this hasn't already been answered, if so I apologize.

I have the factory integrated trailer brake on my 2011 GMC Yukon Denali with the Tow Package.

Welcome to the forum Matt. Does your RPO sheet have JL1? If not, it appears to me that someone attempted to add the factory ITBC to the truck. While not impossible, it would be enormously costly to properly retrofit the ITBC to a truck that did not previously come with it.

If you do have JL1 and nothing comes up on the DIC when you adjust the gain, you may have some electrical problems to sort out to get it running again. You'll need a bi-directional scan tool that can read chassis codes. The ITBC module probably has a malfunction and codes are stored that need to be pulled and viewed. A Tech-2 and the shop manual will make short work of this. Mine is currently acting up, the little SSR, Solid State Relay, is acting up and throwing a code and DIC warning message. Only problem is, someone moved it, and I have yet to find the little booger under the truck!

 

[Matthew Snyder]

Thanks for the replies

Here is the RPO Codes, I do see the JL1 listed;


Here is the Bumper Plug generally undamaged and fairly clean, Fuse panel with the Stud 1 & 2 Fuses intact for the most part (the cover for the 40 Amp has came off while fiddling with it and removing and reinserting but rest assured there is continuity and I will replace with a fully enclosed fuse immediately upon solving my issue before traveling anywhere).



Pictured now is the factory ITCB and the accompanying factory wired harness;

 

[Matthew Snyder]

Here is the previously mentioned wires in the orientation I have connected them myself.



The stud on the left had the pre-existing lower wire that is in the protective sleeve, the wire on the passenger side coming from beneath the Master Brake Cylinder was bunched up and taped with an eyelet crimped on that matched the stud size of the Driver Side Stud, where as the wire on the drivers side was bunched up and taped with an eyelet crimped on that matched the stud size of the Passenger Side Stud where they are both currently connected.

 

[Matthew Snyder]

I have the following 2 parts on order from Amazon which will be here tomorrow

New Controller;
https://www.amazon.com/gp/product/B00B4KNNZO/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1

Relay located between truck and spare tire;
https://www.amazon.com/gp/product/B00559VPK0/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1

Fairly inexpensive however would have prefered to just purchase an aftermarket and install it if neither of these are the cause. Was hoping I was missing a wiring issue or something else needs to be plugged in and avoid having to 'mutilate' the interior and have a redundant nonfunctioning brake controller on the dash.

 

[swathdiver]

Here is the previously mentioned wires in the orientation I have connected them myself.

View attachment 227505

The stud on the left had the pre-existing lower wire that is in the protective sleeve, the wire on the passenger side coming from beneath the Master Brake Cylinder was bunched up and taped with an eyelet crimped on that matched the stud size of the Driver Side Stud, where as the wire on the drivers side was bunched up and taped with an eyelet crimped on that matched the stud size of the Passenger Side Stud where they are both currently connected.

Ok, I think this is the problem, take off the wire that came from the fender. This wire is for an aftermarket brake controller. It may be cancelling power to the factory unit.

 

[PG01]

Ok, I think this is the problem, take off the wire that came from the fender. This wire is for an aftermarket brake controller. It may be cancelling power to the factory unit.

This

 

[Matthew Snyder]

I have removed the wire that was originally bunched up by the fender that I had attached to the Passenger Side Lug as pictured. This resulted in still not seeing any gain settings or messages on the DIC without a trailer connected while pressing the + or - on the controller or actuating the slide rails.. Will connect to a trailer and see if it recognizes anything then, and will update. I guess I am still uncertain if I should get a message on the DIC when pressing + or - on the controller without a trailer connected. It is my understanding it should show what the gain is currently set at regardless of a trailer connected. Can anyone confirm this? That would lead me to think the controller is faulty or it is not being recognized as if an input wire is missing somewhere or if something in the computer has to be turned on to recognize it?

 

[Derick]

Ok, I think this is the problem, take off the wire that came from the fender. This wire is for an aftermarket brake controller. It may be cancelling power to the factory unit.

I dont think this will do anything. That wire just runs 12V into the cabin under the dash, and much like the engine bay its just taped up and out of the way for future use. I dont think there is anything between the ends to give the system any 'logic.' You could power anything with it, it just happens to be set up for a trailer brake controller.