[Rexydg]

mine is a 2019 when I first bought it that was one of the first things I looked at on the lot mine has a plastic stand off that snaps onto the AC line from there it is zip tied to the harness to keep them apart.

looked at mine again and it seems to be routed differently that what I am seeing here. it goes over and in front of the piping on the left here in the pic, not behind. there is a second plastic standoff in the area of the compressor head there however it was not on the pipe still. I wrapped that section of the harness to protect it even though it was not touching. I will keep the TSB on hand.

 

[Rexydg]

So after printing, i went out and checked ALL the other areas that were addressed, they all seem to be fine, the harnesses have been moved, re routed, placed differently to avoid those areas of concern. No electrical issues as of yet, but I am only at 9900 miles. it does not look however as these chafing areas will be a concern although I will keep an eye on them.

 

[mtnseth]

I've had a persistent "Service Trailer Brake" DIC light for about two years, and recently (two weeks) starting picking up a "Service Power Steering" light that went off every 10 minutes or so (when accelerating/decelerating) and now comes on at every start up. No symptoms in function. Dealer attributed bad Body Control Module for trailer brake light due to the code (which subsequently is on the list of codes in the service bulletin). I haven't taken it in for the power steering yet, but I want to avoid one of those major loss of steering at highway speeds or limp mode.

Today I took off the front driver's wheel and found very worn wiring harnesses on the main and accessory branches near the AC compressor, but no appreciable fraying in the insulation of the individual wires. Wrapped in electrical tape and unhooked the battery for an hour, but both DIC warnings returned. I guess I'll give the dealership a crack at it.

 

[92twinturboz]

MY 2019 owner here with similar symptoms. Had a flurry of P2BAA DEF related codes when truck had 12k miles. At 44k miles now, and getting intermittent service 4wd messages. Dealer has referenced the TSB, but haven't found any chafing themselves. I think I'll have to take a closer look myself when I get the truck back if they aren't able to reproduce the issue.

 

[92twinturboz]

Update from the dealer. They identified wiring harness damage on the rear of the engine on the driver side. $1250 to repair the harness at that location. I'm engaging GM Customer Service as a result since this is a known manufacturing defect.

 

[92twinturboz]

It also looks like GM Techlink had an article on the issue in November of this year:

Wiring Harness Conditions on the 2.8L Diesel Engine – TechLink

gm-techlink.com

 

[HalfWatt]

Same problems with my 2019... I've taken it to two dealers. The first dealer's techs were just useless. The second seemed like they were pretty on it and referenced this tech bulletin. I may have to double check their work myself just for piece of mind. It has been fine the last few days but today all the gauges stopped communicating for a couple of seconds. The stabiltrack light popped on and then off for a second and it kicked me out of trailiering mode. Everything then went back to normal. No check engine light. Checked for any codes with a Bosch code reader and nothing. Nothing like paying 40 some grand for a new truck and then this s**t. Been going on for months.

 

[92twinturboz]

Coming back full circle here. GM came through and helped cover the cost of the repair. Drove ~250 miles since the repair and haven't had any issues. Fingers crossed this is the last I see of this issue. @HalfWatt the dealer I used had to disconnect and partially remove the harness to see where the actual damage was, as its not possible to see all the chafing points from a visual inspection with the harness in-place.

 

[HalfWatt]

Thanks for the info @92twinturboz I'll bring that up to the dealer I've been working with.