STOP BEEPING! Service Trailer Brake Nightmare!

Aaustins14 · December 2, 2021

Ok everyone, new here. I tried my hardest to avoid posting because I know that there are a thousand threads on the internet regarding the chime for "Service Trailer Brake System" and "Check trailer wiring".

I have intermittently had the Service trailer brake system and check trailer wiring warning come on the screen for maybe a year. It would pop up maybe once or twice a month.

The problem is that this week it must have went off hundreds of times. It has never gone off while pulling a trailer, it only ever happens driving empty.

Today on my drive home from work it chimed at me from key on to key off when I got home. It was very rainy so could be a wiring issue.

It beeps back and forth between the two warnings the entire drive.

The truck does have a brand new 7pin/4pin trailer connector I installed in the rear bumper, so I know it isn't that.

I also unplugged the Trailer Brake Module above the spare tire and cleaned and added dielectric grease.
I looked for corroded wires but did not see any. Is there a particular place to look?

Any help is appreciated, I'm at my wits end.

Thanks in advance

EDIT : Forgot I scanned the chassis control module.. Came up with these codes:

c1114-00

c1115-5a

c1116-00

c1117-00

u1556-0

EDIT: 2014 GMC Sierra 1500

Edited December 3, 2021 by Aaustins14
ADD INFO

M1ck3y · December 2, 2021

For what its worth, Good Luck :thumbs:

Aaustins14 · December 2, 2021

Thanks Mickey

mikeyk101 · December 3, 2021

Standard disclaimer, I am not a trained mechanic, just a Jack of all trades... Doing a quick search on those codes show that most all point to a short circuit or open circuit. I saw several posts that it could be as small as a nick in a wire that touches a ground and can be a bit tricky to track down. The last one points towards the Chassis Control Module. I came across several sites that talked about water intrusion and that once that happens, the only cure is to replace it. And I also came across this article. I'm taking a WAG that yours is a 14 based on your user name. But take a look at this: https://www.google.com/amp/s/www.motortrend.com/news/1410-gm-cars-trucks-suvs-recalled-for-chassis-control-module-defect/amp/

OffTheAir · December 3, 2021

Oh GOD. Yeah, I know exactly how you feel with this one. This plagued my truck during my first year or so of ownership and it drove me absolutely insane. It came back for the first time in years last month and I thought it was going to start doing it again, but luckily it didn't.

If you've already taken the necessary steps with the module above the spare tire, I would definitely look into possibly the actual manual trailer brake module itself being faulty. In which case, it is as simple as just removing the bezel and replacing the part. There's a couple videos on YouTube that detail this process that are as short as 3 minutes and are incredibly helpful.

I apologize in that I cannot verify if this will truly fix the issue as these are not the steps I personally took to get rid of mine (I actually went ahead and replaced the fuse and that seemed to work), but it does seem to have worked with a lot of people with the c1117-00 code and should my warnings ever come back this will be the next step I take.

Aaustins14 · December 3, 2021

@M1ck3y I have checked over a lot of the visible wiring harness and found nothing. A lot of the harness is covered in wire loom so it is hard to tell, but I didn't see any chaffing.

My understanding with that last code was that the Chassis couldn't talk to the Trailer brake module..? I guess it could be either of them or wires in between. Someone would have to really understand the system and how their networked to figure that out.

That article only references the 2013/14 Silverado/Sierra HD trucks.. So wouldn't be applicable. Thanks for the ideas

@OffTheAir Yea. Its driving me nuts. I did check all the fuses that seemed to be related to anything trailer or braking and they were all ok.

I will look into the on dash controller.. Maybe ill try unplugging it and see if it improves.

Thanks for all the ideas. They are appreciated.

Aaustins14 · December 4, 2021

OK, So I unplugged the manual trailer brake controller in the cab.

Now the only warning is the warning immediately after I start the truck. This warning was there before I unplugged it.

Drove around today with no issues except the warning on startup.

I am hoping that the controller is the issue. My other thought is that with it unplugged the entire trailer brake system is disabled and thats why the warnings stopped??

I am going to order a new one and see what codes remain after installing it.

Aaustins14 · December 7, 2021

Update...

So I got the new manual brake controller and installed it.

Nothing changed, seems to be reacting the same. Randomly throwing "Service trailer brake system" and "Check trailer wiring."

It doesn't seem to be linked to movement like a chaffed wire. It happed a handful of times before I even put it in drive.

It also happened sitting at a stop light after I had been sitting there for a while.

Checked again for bad/chaffed wires.

Should I just bite the bullet and order the trailer brake controller?? I really hate the brake out the parts cannon.

Any suggestions are much appreciated

mikeyk101 · December 7, 2021

Take a look at this page. There are a slough of TSB's related to your issue and maybe one of them will help with the fix

https://www.aboutautomobile.com/Technical-Service-Bulletin/2014/GMC/Sierra-1500/Integrated-Trailer-Brake-Control

mikeyk101 · December 7, 2021

And it's a possibility mentioned in one of the first few TSB's but take a look at your battery. Many weird electrical issues cane be a result of the battery. Is yours still the original? If so, I would be looking at replacing that before you go further as it will be over 7 years old now. And if you have a more current battery, sometimes just disconnecting the battery for a bit helps reset and resolve strange issues.

Aaustins14 · December 7, 2021

I will go through those.. Thank you. Nice website to keep bookmarked.

One thing I do notice is that a lot of the TSB's are talking about this issue when a trailer is connected. I have no trailer connected.

I did think about electrical/voltage issues. I can check the age of the battery after work tonight. I have not had any long cranks or old battery indicators, but worth a check.

17heavychevy · January 27, 2022

i am having a similar experience. did you ever get this resolved??

Aaustins14 · January 28, 2022

Well I currently have the In-cab trailer brake controller unplugged. This stops the constant beeping, now it only beeps once when the truck is started.

My battery seems fine. Voltage was fine. and the truck has been starting just fine in the -5f degree weather.

I am believing that it is the trailer brake control module that is under the truck/above the spare tire.

I have not gotten around to changing it out, mainly because it is a frozen tundra out there.

I already changed out the in-cab controller and the connector on the back bumper.

If is is not the control module, then I probably have a bad wire hardness somewhere.

ember1205 · February 9, 2022

I've had this same sort of issue in my '15 Silverado for about two years. The issue will appear, drive me crazy, and then go away just as quick and not come back for quite some time.

I had a water leak into the cab through the third brake light (common issue). I pulled it all apart, literally shook the water out of the light housing, then re-installed with a brand new seal. The problem didn't recur on me for close to a year, but it has been back a few times.

I have also replaced my battery as mine just up and died on me in the middle of summer at one point. That didn't help.

I've pulled the controller module down from above the spare and checked it closely - there seemed to be no evidence that water had made it inside so I just reinstalled it.

I'm torn as to whether I actually want to chase it to fix it or just leave it and it will go away when I get rid of the truck. Given that I do not tow any more, I may disconnect the brake controller if it comes back to a point where it won't stop.

FWIW: Mine is most likely to act up and persist with very cold weather (it first started after my truck was parked at the airport for three days in below zero weather).

Aaustins14 · February 10, 2022

My third brake light leaked on the previous owner, I have some water stains to prove it. It seems he must have fixed it because it has not leaked in the time I have owned the truck.

Winter here in Western NY.

I think you may be on to something with the cold weather. I did notice it started happening repetitively once the temperatures dropped.

I still need to order the control module, but I would also like to order that connector and do both of them. Just cannot seem to find the connector online or even a part number.

I do think that my issue is from the control module. Either water got in, or it just failed on its own.