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Service trailer brake

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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.



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

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