Installing aftermarket brake controller with factory ITBC (JL1)

[dkad260]

Might have to reconfirm this statistic, this does refer to half-ton models correct?

 

[dkad260]

Some interesting findings...

I ran a scan on all the modules, after the scan started, I got the "Service "Stabiltrak" message on the DIC.

Final results were 2 codes,

Rear heated seat module B1925


C0045 left rear wheel speed sensor.

Safe bet the speed sensor will mess things up.

Next, I checked the blue blunt cut wire under the dash for continuity to the 7-pin and there was none. Nothing to the 6-pin connector at the relay above the tire, or to the 7-pin.

Also, the mystery relay under the brake booster shows no continuity to the blue blunt cut wire.

I'm assuming the wheel speed sensor was acting up but hasn't stored a hard fault yet.

 

[swathdiver]

Might have to reconfirm this statistic, this does refer to half-ton models correct?

Yes.

Is the C0045 an active or historical code?

I don't think those wires are original. 2009 was an intermediate year and that is why I asked some of the guys with newer trucks with JL1 to chime in to see if they have that stuff.

 

[dkad260]

I'm going to guess an active since I have run this test a few weeks ago and there were no codes. Interesting about the seat heater also.

This was the screen.

 

[gooffeyguy]

@swathdiver I have that relay on that wiring harness under the master cylinder on mine, but I also don't have the JL1

 

[Joseph Garcia]

Good discussion here. Unfortunately, I have nothing to contribute to this topic, as I've never towed anything that needed a brake controller.

 

[gooffeyguy]

I'd be curious where these underdash brake controller wires are disconnected if you have the JL1 (ITBC) option and if it's just a plug type connection where the other is plugged in and just needs to be swapped

 

[swathdiver]

I'm going to guess an active since I have run this test a few weeks ago and there were no codes. Interesting about the seat heater also.

This was the screen.

View attachment 377667

Yes, that is a current code. Try clearing it and see if the ITB works before it sets again.

 

[swathdiver]

@swathdiver I have that relay on that wiring harness under the master cylinder on mine, but I also don't have the JL1

Right, when I saw your post I went out to my truck and had a look and don't have what you have which makes sense I think.

 

[dkad260]

Yes, that is a current code. Try clearing it and see if the ITB works before it sets again.

I cleared the codes, still no trailer recognition.

 

[Geotrash]

So, I do have JL1 on my 2012, and I also have that relay beneath the brake booster.

 

[dkad260]

Just to clear things up, this thread is a spinoff from my other thread on the factory brake control not recognizing the trailer, found here:

https://www.tahoeyukonforum.com/thr...ke-controller-not-recognizing-trailer.135900/

I've tried to get the Yukon to see the trailer, now I'm working on an aftermarket brake controller in hopes to get some work done around the home.

I appreciate everyone's input.

 

[dkad260]

I'd be curious where these underdash brake controller wires are disconnected if you have the JL1 (ITBC) option

Yes, this is a good question.

I want to assume GM at the LEAST, ran the blue wire to the other side of the firewall.

Would be real nice if they ran it back near the 7-pin connector.

I will check tomorrow in hopes it's near the 7-pin.

I don't like to cut any of the factory harness. So my plan is if in fact I have to run a length of blue wire, is to fabricate a piggyback connector that dead-ends the factory blue wire from the ITBC, and allows me to add the aftermarket blue wire while maintaining the integrity of the factory harness. This way I can reverse the hookup and return to stock at a later date.

Should be fairly straightforward with a USCAR connector to loose wires, 7-pin connector, and a 7-pin trailer plug.

 

[dkad260]

Finding out where this blue wire terminates would solve alot of problems..lol.

A big mystery.

 

[swathdiver]

Finding out where this blue wire terminates would solve alot of problems..lol.

A big mystery.

View attachment 377825

Where is in those diagrams posted, it does indeed go all the way back to the 7-pin connector.

 

[dkad260]

The blue wire under the dash is a darker shade than what goes to the 7 pin.

From what I can tell, the wire that goes to the 7 pin goes to the relay and to the fuel pump module.

 

[dkad260]

The pics in this file have been shared, but check out the text regarding the JL1 option.

https://static.nhtsa.gov/odi/tsbs/2019/MC-10155069-9999.pdf

These are the two terminals listed for connection into connector X126 or X115.

15304732 Part Detail | TTI, Inc.

www.tti.com

15304720 Part Detail | TTI, Inc.

www.tti.com

These are the two terminals listed for connection into connector X126 or X115

The big question is the location of this terminal.

 

[swathdiver]

The pics in this file have been shared, but check out the text regarding the JL1 option.

https://static.nhtsa.gov/odi/tsbs/2019/MC-10155069-9999.pdf

View attachment 377836


These are the two terminals listed for connection into connector X126 or X115.

15304732 Part Detail | TTI, Inc.

www.tti.com

15304720 Part Detail | TTI, Inc.

www.tti.com

These are the two terminals listed for connection into connector X126 or X115

The big question is the location of this terminal.

I think you've solved the mystery on how to undo JL1 and run an aftermarket controller. Nice work detective!

 

[dkad260]

The plan was to install an aftermarket controller, while maintaining all the factory connections and the use of the ITBC at a later time if desired. I didn't want to drill any holes if possible, or cut any of the factory wires. Overall it's not much different than any other brake controller install.

For this project, I picked up a second harness for the Prodigy and temporarily swapped my old P2 controller from my other vehicle to make sure all would work first.

I used:

Curt 56229 replacement USCAR connector wiring harness
Curt 55415 OE 7-way RV blade socket. I wasn't sure if I needed the mounting holes but others will work.
Curt 58140 7-way plug
Approx 25' of 12 gauge wire and 3/8" wire loom

I have no idea where the factory blue wire terminates, so I just ran it from the aftermarket controller

Getting through the firewall grommet was a chore, I used a Klein fishing rod with a loop end. Having someone else to force it through while trying to keep it from poking through the grommet was a bit of a pain but all worked out.

​

Removing this brace helps quite a bit.

I did tape up this wire and the end of the factory grommet before taping up the wire loom.

 

[dkad260]

I kept the factory 7-pin harness intact, and plugged it onto the new socket. The other end where the new 7-way plug attaches, I left out the blue wire from the new USCAR wiring harness. The blue wire from that harness was connected to the new blue wire from the brake controller. If I need to use the factory ITBC, I can cut a few zip ties and reconnect to the OE socket.

For the controller, the single screw for the panel was more than adequate to keep the controller secure. I used 2 pieces of adhesive backed pad that is somewhat grippy on the other side. This will keep the controller from twisting and won't stick to the factory panel.