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-   -   Question: LMM:Disable "Service Trailer Brake System" message (https://www.dieselplace.com/forum/76-speciality-forums/222-towing/966746-lmm-disable-service-trailer-brake-system-message.html)

Potent68 06-28-2018 12:45 PM

LMM:Disable "Service Trailer Brake System" message
 
I've done some searching but it all leads to people's attempts to fix their ITBC, some successful, some not. This is not a troubleshooting the ITBC thread though.

Mine worked well for 9 years or so and then about 15 months ago the problems started. Now they can't figure out what the problem is and referred it to the GM engineers. 15 months ago they replaced the trailer brake control module.
I'm considering just installing the Prodigy P3 and being done with the factory system.

My question is, has anybody found a way to disable the "Service Trailer Brake System" message after they install an aftermarket trailer brake control module? If I have to live with the error message on the dash I'll probably dive deeper into the factory ITBC than I really want to.

heymccall 06-28-2018 01:42 PM

Yes. Even your dealer has access to the itbc disable instructions.
I definitely need to know what year.
Really, if they haven't changed the output relay, that's inexpensive and easy.
Did anyone actually give you the fault code(s)?
In reality, the system is butt stupid.
It does, however, make a difference as to what year your truck is, as well as whether or not the UY2 RPO code is listed on the glovebox sticker.

As for the disable instructions, along with aftermarket installation, I have that info in a thread on here somewhere. I'll link to it tonight, but, for certain, you do have to run a new output wire to the rear of the truck (blue wire).

Potent68 06-28-2018 03:27 PM

That's great news. Thanks! It's a 2008 3500HD SLT CC LB SRW 4WD.

A buddy and I pulled the codes with his SnapOn scanner but I don't recall what they were now. I'll either follow up with the dealer about what codes they pulled or see if his scanner stored them.

We checked all the inputs and everything seemed proper. My suspicions are that it's another bad module, but being that it was replaced 15 months ago it's past their 12 month warranty. I actually spun wrenches for years for the dealers when I was young and frankly, that's part of my annoyance. Unless I spend a lot of money on something like my buddy's Snap On scan tool, I can't read codes like these, you can't program the TCBM , I can't properly troubleshoot on my own, you can't program the TCBM (or is it programming the ECM to the new TCBM?). :(

For the cost of one dealer visit I can have the aftermarket solution in place and not have to worry about the dealer again. :D

heymccall 06-28-2018 03:49 PM

The odds of actual module failure are like 1 in 1/2 million. The odds of two, well.......
On an '08, there is a solid state relay mounted on the left frame rail, inboard. The bolts are accessible through the left rear wheelhouse. That relay, on your age of truck, is suspect. Relay failure is tremendously more common. Usually from environmental exposure (moisture entry and subsequent swelling and rusting).
Before buying aftermarket, remove and inspect that. Two M6 bolts with 10mm heads. The holes in the frame are slotted, so the bolts only need loosened, not removed.

Also, if the underhood fuse for output is blown, (not the little one), you'll get the same error.
Again, I'll post the disable instructions tonight.

heymccall 06-29-2018 02:35 AM

Open the PDF in post #21 here https://www.dieselplace.com/forum/76...ml#post3119055

Oh, and discard the "ITBC" 10amp fuse underhood after you wire up your P3.

Potent68 06-29-2018 02:30 PM

Thank you sir! I went ahead and ordered a relay just in case. It will be here tomorrow.

heymccall 06-29-2018 02:40 PM

See...this is a "fix my itbc thread" after all.
The fault codes that led to suspecting the itbc module would've helped, but...
If the 10amp ITBC fuse underhood were blown, no ITBC, but also no message
If the relay is bad, ITBC message comes up.
If 30amp fuse underhood is blown, same message
If the gain control under dash is accidentally left unplugged (due to panel r&r), same message.
If there is an ABS fault, same message, but also ABS message
If the UY2 option is present, and the blunt cut wires are shorting, same message.
If excessive corrosion exists in bumper plug, same message.
If the master cylinder pressure switch is bad, no message.
If stoplamp switch is failed, no message.

The output relay on the frame will be questionable, especially if the bolts are rotted, and if the plastic housing is swollen.

Potent68 06-30-2018 09:29 PM

I replaced the relay to no avail, unless you somehow have to clear the code first. The 10 amp ITBC fuse is good. The 30amp Stud 2 fuse is good. I verified both with my ohm meter. The kick panel hasn't been off so I doubt the gain control is unplugged. No ABS message. No corrosion in the bumper plug. I actually added dialectric grease to it the last time this happened just to be safe.

We do have the UY2 option, but I'm not sure what wires you're referring to as "blunt cut". It sounds like it's either that (the mechanic said he checked all the wiring) or I am the unlucky recipient of a bad module.

Thank you for your help thus far.

Potent68 06-30-2018 09:52 PM

I went ahead and popped my kick panel off real quick and confirmed that the harness is securely plugged into the controller and the message is still present.

Mr Dawg 07-01-2018 07:48 PM

I had the same problem on my 09 and couldn't figure it out for about 2 years. Turns out it was speed sensor. When I replaced my front hubs the light went out and hasn't been back for the last 1.5 years.


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