Towing a Trailer issue's

Hello AT4 Forum,
When i hook up my brand new trailer im having several issues the dealer cant figure out.
As im driving the screen where the gauges are reads trailer disconnect, then all the lights go out on the trailer.
sometimes this also makes the infoliant screen go black and all the instrument cluster gauges. the radio still plays but it all goes black.
after a couple minutes the screens come back on. The screen then reads, quest trailer recall has not been done. 90 percent of the time the trailer lights come back on, sometimes they dont.
It is very risky driving like this. Every other time i use brakes or blinker the same scenario happens.
The issue has been worse since i had the software recall done last year.
its been to the dealer three times for this issue, every time they hook the truck up to the trailer simulator they say everything is working correctly.
they are now going to replace the whole 7-pin assembly in a couple days.
I have hooked up my trailer to several other vehicle's and have had no issue, so im pretty positive it is my truck.
I have read about quite a few trailering issues but not with the lights going on and off issue im having with the screens.
Hopefully this all makes since, any one else having or had this issue?

Is your hitch powder coated? Mine was which prevented it from grounding properly. Trailers ground through the hitch unless you wire a specific ground. Surface rust inside the trailer side of the hitch can cause connection issues also. I just removed some of the powder coating on the top portion of the hitch and it fixed my problem.

I am not sure to be honest, i will look into that and if it is i will do some sanding this weekend and report back on that.
thanks for the info.

I’m having what sounds like the exact same issue with mine. I’ve got two trailers in it does it on both of them. One of the trailers is brand new. I’m at 7500 miles and I’ve tolerated it up until now but I think I’m going to declare it as an issue the next time I’m in for service.

among other things the bell just keeps ringing while I’m driving which is beyond annoying.

it should have nothing to do with the fact that your metal is powder coated. The 7 pin has a ground inside of it for this very reason.

RAINCO said:

I’m having what sounds like the exact same issue with mine. I’ve got two trailers in it does it on both of them. One of the trailers is brand new. I’m at 7500 miles and I’ve tolerated it up until now but I think I’m going to declare it as an issue the next time I’m in for service.

among other things the bell just keeps ringing while I’m driving which is beyond annoying.

it should have nothing to do with the fact that your metal is powder coated. The 7 pin has a ground inside of it for this very reason.

Click to expand...

Agreed, but if the trailer wiring doesn't ground in the plug, it could cause that issue. Did with mine. Hope you figure it out.

You are probably right. I broke a seven pin one time and had to basically rebuild it and I remember there being a ground in it. I just assumed there was a ground it went up to a grounding contact somewhere in the vehicle. You are probably right though at a more technical level.

I certainly hope that the towing feature on a $60,000 vehicle isn’t essentially worthless because of powder coating.

This is my first GM product and I bought it mostly on brand before I even saw an AT4.

Hopefully this gets resolved for all of us.

My trailer is powder coated, i got the new 7-pin connector on from the dealer and i will hook up this weekend and see if that helps.
I was told to take off the grounds on my trailer, do a little sanding to get the bare metal showing then reinstall grounds.
I did that this week so this weekend will be the big test weekend! cross those fingers and toes.

Update, dealer put in a new 7 pin blade connector and no fix, GM does have a bulletin out now about towing issues. GM actually suggests putting in some incandescent light bulbs to make a higher draw so the trucks system recognizes the trailer, or this led light trailer adapter, Curt pt# 57003.
So i bought this led light trailer adapter. Problem solved! just did a 200 mile long camping trip with lots of brake and blinker usage, no issue's at all.
let the world know that there is a fix out there! I'm so freaking happy!

Sharing this response because I've thought it was a towing issue from the get go...

That's great that you've found a solutionMachoMan. If that fixes it long term, then that is excellent. And, thank you for sharing, including pic.

I can't help to shake my head though at a $60K vehicle that needs a 3rd party piece of duct tape to make it work. Surely GMC is capable of a better solution. Surely duct tape and plastic fixes are not what it takes to make these spaceships reliable.

I got my truck out of the shop just over a week ago w/ 7K miles. They swore the "trailer diagnostic tool" didn't detect any issue and that it "has to be the trailer". Nevermind the fact that it was 2 different trailers, one of them 1 week old. Top of the line LAMAR w/ top tier wiring components.

I had originally checked it in for a clicking motor, missing, shaking and random error notices when a trailer was hooked up. Got an Onstar notice on the way home from the dealership that there was an "issue w/ the emissions system." I was grateful for the Onstar notice b/c it essentially immediately invalided the blow-off I got at the dealership the first time. ($2200 of replaced "lifters" (dealer cost, mine would be $3K-$3.5K? if out of warranty))

Took 1/2 day off today and trailered my single axle trailer (2Klbs GVW and an ATV 500lbs)
4 miles up the road and the dash cluster looks like a Christmas tree:
-"Service Parking Brake"
-"Service ESG"
-Traction control light lit
-Check Engine Icon blinking, solid, then blinking again
-Parking brake w/ wrench under it lit up

Got any another suppository loaner. If I was using this truck to make a living, I would be in serious trouble. But "Professional Grade," right?

Tech says this time the diagnostic tester acknowledged codes for the motor and a second set of codes for the trailer wiring - and this he says, "substantiates 2 completely different issues." I'm thankful for something "they" consider "credible" validation of what I was saying almost a month ago now.

I'm grateful they are helping to resolve it, but struggling w/ GMC honestly.
Never had a vehicle w/ this experience. It's probably caused by emissions systems - Govt EPA.

Machines break. But, what I cannot (and will not) tolerate is being blown off.

I applaud the guys who own it at the moment, and are working to fix it.

How in the world you have confidence in one of these machines after you are out of warranty is beyond me.

Maybe that's the whole point though. Keep the people buying new vehicles b/c they can't afford to be out of warranty.

I used to think extended warranties were a waste (of course that came w/ the assumption that products were quality and built to last)
But in a world where they obviously are not, perhaps a prudent customer DOES buy the extended warranties.

I'm just pondering the most practical way to approach this in the long-run.

This entire issue is being caused by a load being put on at the motor. 2500lbs of gross trailer weight; truck is rated for 9200.

i agree that our Very expensive trucks should not have this issue, or any.
i was so bummed out for so long about it that when i saw that gm recommends using this part for a fix i was ready willing and happy to be able to tow again.
gm should have known that newer trailers are going to be all Led. The trucks are Led so why not the trailers? it is very frustrating indeed.

RAINCO said:

Sharing this response because I've thought it was a towing issue from the get go...

That's great that you've found a solutionMachoMan. If that fixes it long term, then that is excellent. And, thank you for sharing, including pic.

I can't help to shake my head though at a $60K vehicle that needs a 3rd party piece of duct tape to make it work. Surely GMC is capable of a better solution. Surely duct tape and plastic fixes are not what it takes to make these spaceships reliable.

I got my truck out of the shop just over a week ago w/ 7K miles. They swore the "trailer diagnostic tool" didn't detect any issue and that it "has to be the trailer". Nevermind the fact that it was 2 different trailers, one of them 1 week old. Top of the line LAMAR w/ top tier wiring components.

I had originally checked it in for a clicking motor, missing, shaking and random error notices when a trailer was hooked up. Got an Onstar notice on the way home from the dealership that there was an "issue w/ the emissions system." I was grateful for the Onstar notice b/c it essentially immediately invalided the blow-off I got at the dealership the first time. ($2200 of replaced "lifters" (dealer cost, mine would be $3K-$3.5K? if out of warranty))

Took 1/2 day off today and trailered my single axle trailer (2Klbs GVW and an ATV 500lbs)
4 miles up the road and the dash cluster looks like a Christmas tree:
-"Service Parking Brake"
-"Service ESG"
-Traction control light lit
-Check Engine Icon blinking, solid, then blinking again
-Parking brake w/ wrench under it lit up

Got any another suppository loaner. If I was using this truck to make a living, I would be in serious trouble. But "Professional Grade," right?

Tech says this time the diagnostic tester acknowledged codes for the motor and a second set of codes for the trailer wiring - and this he says, "substantiates 2 completely different issues." I'm thankful for something "they" consider "credible" validation of what I was saying almost a month ago now.

I'm grateful they are helping to resolve it, but struggling w/ GMC honestly.
Never had a vehicle w/ this experience. It's probably caused by emissions systems - Govt EPA.

Machines break. But, what I cannot (and will not) tolerate is being blown off.

I applaud the guys who own it at the moment, and are working to fix it.

How in the world you have confidence in one of these machines after you are out of warranty is beyond me.

Maybe that's the whole point though. Keep the people buying new vehicles b/c they can't afford to be out of warranty.

I used to think extended warranties were a waste (of course that came w/ the assumption that products were quality and built to last)
But in a world where they obviously are not, perhaps a prudent customer DOES buy the extended warranties.

I'm just pondering the most practical way to approach this in the long-run.

This entire issue is being caused by a load being put on at the motor. 2500lbs of gross trailer weight; truck is rated for 9200.

Click to expand...

I feel for you, but unfortunately, this is just the reality of modern vehicles. There are thousands of microprocessors in our trucks that work interconnected, so if there's one bad lead, crap like what you continue to endure will happen.

If you don't want to run the risk of these issues, you might want to try to rebuild a K5... that's what I'm trying to set myself up to do. We can sit here and curse ephemeralization until the cows come home, but we need to understand that advancement never comes 'without' a cost. I love all my cameras, sensors, LED lights, computers, and butt fans... but at what cost?

Good luck in the fight, brother! Good news is, with the chip shortage and truck demand, maybe the buy back is easier since they can either vulture the chips there, or replace a couple and sell it again? Not that it's a great option, but I bet you'd have little issues selling it, folks are desperate right now. Maybe someone in your area wants an AT4 and had no intention of ever trailering?

Just keep your head up man, I know it's draining.