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HELP! "Service trailer brake"

3K views 14 replies 9 participants last post by  knotReally 
#1 ·
Hey guys, so the other week every time I start my truck it started flashing "service trailer brake". It started about the same time I noticed my brake switch going bad, so I changed that out and it didn't take care of the service trailer brake message. I tried cleaning out the plug on the trailer brake control module thinking there was corrosion or something but that didn't to it either. If you guys have any other ideas or comments I would be glad to hear them. Thanks guys
 
#3 ·
I changed the TBCM & the brake switch. No go! Scanned for ABS codes and there were multiple C0035. R&R’d front driver side wheel speed sensor and all is good now!


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#4 ·
This was what fixed mine also in a round about way. I changed the wheel bearing on the front drivers side. Then kept getting the trailer brake codes. Changed it out again, because it was under warranty. Still no good. Finally chased it down to being the parts store. They kept giving me a bearing for a 2007, instead of the 2007.5 that it is. The wheel sensors are different for that particular year. Have not had any problems with it since.


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#6 ·
Having the ABS light lit causes the Service Trailer Brake System message to be displayed in the DIC. Fix the ABS problem and the STBS message automatically goes away.
 
#7 ·
UPDATE: So far I have replaced the trailer brake control module relay, cleaned and put some dielectric grease on the large plug right next to the relay. And I have checked the other plugs for the trailer hookup for broke terminals or corrosion and didn't notice anything. If anyone has any other ideas I would be glad to hear them! Thanks again guys!
 
#8 ·
When you changed your brake switch, did you use OEM or aftermarket? If aftermarket you may want to try OEM. Also check your high mounted brake light - if it doesn't work, your trailer brakes won't either. Did you have an indication that the TV relay was bad? or just changed it to see if that was the problem?
 
#9 ·
I bought a switch from my local NAPA dealer. To be honest I never looked to see it my third brake light works or not. I changed out the relay just because I have read other peoples posts and the majority said that, that ended up being the culprit. Other people said that they found out that the problem was a bad wheel speed sensor but I don't think that's the case because I don't have a brake or ABS light on at all.
 
#12 ·
Ive had same problem replaced relay by the rear end went away for a while now its back. Going to talk at e-trailer see if they have a kit to run all new wire and components from up by the cab back. I think the salt etc. has taking over!
 
#13 ·
They won't, it will only be found at a dealer. gmpartsdirect.com is a good source
 
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