Service trailer brake

RickertsRed · June 20, 2019

On 2019-06-12 at 10:11 PM, RickertsRed said:

So I’m reviving this thread because I had a very similar issue just recently and the fix was simple so hopefully it’ll help you guys.

My ‘17 Sierra 3500 started with the quite common door ajar issue, I tried slamming it, playing with the accordion wire harness in the door frame, I even took the door panel off and pulled apart all the connectors to see if there were loose or frayed wires or possible corrosion. Pulled out a multimeter and checked everything; all good. None of the above fixed my problem.

Then I started getting the “service trailer brake” and “trailer disconnected” randomly. Sometimes with a trailer attached, sometimes without. Seemed odd to me, but I didn’t even bother troubleshooting.

Next I started getting “Service Stabilitrak” randomly and sporadically.

Ok ok now I’m thinking WTF is going on here. So I disconnected both batteries and pulled every single fuse and reset it (checked to see if it was popped in the process). I didn’t even check to see which fuse I pulled, just pull, inspect, replace.

The length of the whole battery and fuse process took me about 2 beer, throwing a ball for the dog periodically, playing referee for two toddlers who love to fight and VIOLLA... the door ajar, trailer brake, and stabiltrak all fixed in one swoop.

Hope this helps the next guy.

UPDATE

I did my fuse/battery trick and all was well for 2 weeks... until it rained, heavily. Service Stabilitrak and Service Trailer Brake were back, so now I know 100% it’s a broken wire or loose connection that water is getting into.

So I broke down and went to the dealer to have the codes read and there were a few codes. One for a Chassis Control Module (CCM), one for Body Control Module (BCM), and the last was right rear ABS wheel speed sensor.

Back home I go and crawl under the truck by the right rear wheel and track the wheel speed sensor harness back to where it connects to the truck side via a connector attached to the frame. Ended up finding one of the wires on the truck side about 1” back from the connector with a pin hole in the coating with clear evidence of corrosion in and around the hole.

I could have just re-spliced the wire back together but I’m an avionics technician and we’re not allowed to splice a wire that close to a connector, so my OCD spilled over into this repair and I ordered a whole new connector. ABS wheel speed sensor connector (truck side) info:

part number: S-1895 Pigtail

brand: Standard Motor Products

Spliced on the new connector and presto... fixed again! Luck had it that it was raining the day I did the repair so I went for a drive afterwards, no issues at all. All good!

hope this helps

davester · June 20, 2019

thanks for posting your fix.

Tahoe02 · June 20, 2019

^ +1

Tyler95 · February 15, 2020

So i have a '16 GMC Sierra and just out of the blue driving along the service stability light goes on and then the service trailer brakes light and ABS light comes on and continually keeps coming on! Any help would be greatly appreciated! TIA

Jminter6001 · October 1, 2023

On 10/14/2016 at 8:57 PM, HeliMark said:

I have a '16 2500 DMax. Been pulling a 10K pound toyhauler ('16 Forest River Stealth), but the every so often, I get a "service stabilitrac/trailer brakes/abs" warnings. First time was after towing for about 600 miles, was able to get it to reset, than again after towing 3K miles, 800 miles, and so on. No real rhythm. Of course when the "service trailer brakes" comes on, I lose the trailer brakes, which has not been a big problem getting it off the road after that, but lucky I have not had an emergency while they were inop. Everything will reset after pulling the trailer plug, doing a dance, plugging and pulling the plug again and another dance and drive about 50'.

So far on the first one, the dealer replaced half of the trailer plug on the truck saying they found water in it. The other times, one dealer (mid trip) said I had a bad ABS module, but could not repair it at the time, and that the truck had codes for all the wheel sensors/abs/tranny and a couple of others. When I got home, the dealer here found one of the front calipers sticking, which had caused a warped disc. They ended up replacing the caliper and disc, regrind the other front disc and all new brake pads. They also found some unusual readings in the trailer plug, and ended up replacing the whole plug this time. They said the ABS was good.

After all that, I had to tow my trailer to a dealer for a warranty repair on the refer. After driving about 10 miles, all the warnings went off, losing the trailer brakes again. The refer had a bad thermo disc and thermo wire (both 12v), and when I pulled it home after the repair, no warnings.

So, here is my question. Could the bad thermo wire in the trailer cause some wonky voltage to backfeed to the truck, and cause the truck to go nuts? With all the new electronics, I know any abnormality can cause issue's.

Now that I have the trailer repaired, I have an appointment set up to see the dealer with the trailer hooked up and see if the computers can find anything.

Mark

Did you ever pin point the problem? Im having a very similar issue.

davester · October 1, 2023

....just fyi, that is a 7 year old post (when this thread started), and that user hasn't logged into the site in 4 years. You aren't going to get a response from that user.

And did you read through the thread for how other people fixed their similar problems?

Edited October 1, 2023 by davester