service trailer wiring warning

[Jingle]

We just returned from a trip to the beach and on the way home got a "trailer brake failure" warning and the trailer brakes quit working. The warning on the dash still came up with the trailer disconnected. After a white buckle ride home I took my GMC to the dealership and they replaced the brake control module and the 30 amp fuse. I hooked up to the Monty and still have a "service trailer wiring" warning coming up on the dash.



The only thing not working are the trailer brakes. I checked the grounds an everything is fine. I checked the plug and was showing continuity between pins 6 and 7. I disconnected the ground and was still showing continuity. I replaced the plug and still have the same problem. Where do you recommend I go next? I think I may have discovered my hobby this weekend 🤔

[Ram Montana High Country]

were the parts bad they changed out? I had a failure - the safety cable came unplugged, ruined all the brakes, change brakes, bearings, races, drums and time.


Several have had the wiring that goes thru the axle rub thru and grounded out - can check it with a meter or call and rv tech

[AZ Traveler]

You likely have a shorted wire on one of your brakes. Sometimes one chafes rubbing the insulation off. Pull the wheels and drums one at a time to take a good look as well as looking at where the wiring goes into the axle.

[Jingle]

The GMC dealership did say the controller was bad and before I took it to them I was getting a warning with the RV unplugged from the truck.

[Jingle]

That sounds like fun for in the morning ��

[ChuckS]

A quick check with multi meter at the fifth wheel connector between pin 2 and ground may shed some light to your issue. Should read about 13.5 to 16 ohms. The 4 brake magnets are wired in parallel and when checked at each magnet with wires removed will read 3.4 to 4 ohms each.

If your reading at RV plug is way off then you have an issue with one or more magnets

[Jingle]

Just got back from the RV dealership. They tested the truck by plugging in to another RV. The truck is fine. We have an appointment on Thursday to have them look at the Monty. I talked at length with the tech that does the warranty work. He thinks it is shorted out on one of the wheels where the wire enters the hub and goes to the magnet. He will use an amp clamp to determine which hub to pull after engaging the brakes with the battery connected and the brake safety pin pulled. I hate to throw up my hands and take it to the dealership, but I don't want to crawl around for 3-4 hours when they are set up to do it. Thanks for all the help here. I'll let you know what they find. BTW l was getting about 0.3 ohms between the brake wire and ground.

[uhftx]

I receive this warning even when not towing. GM silverado Service trailer brake control.
It is not raining or anything. The message just crops up. I have had this message when towing also. That is scary. Press brakes and press harder to get the rig slowed down. Is this a NTSB hazzard upon the behalf of GM.
Any advice. IT is now out of warrantee so what is the solution. 2016 model GMC