2017 Freightliner cascadia trailer brakes smoking, not disengaging, caused by something to dotractor

Like I asked above, the ABS... You need the software to properly diagnose. I bet that is it.

 

It may be a bad ABS module in the tractor. Any dealership should be able to diagnose. You never mentioned what brand/model of tractor you are driving... ?

 

LOL! I just saw that! A TA truck stop should be able to handle the ABS diagnoses, but I would call around first on your way back... Talk to a service manager and go with your gut. Call more than one if you cannot get it into a dealership.

 

I can't really see how ABS would cause this. The ABS doesn't magically add air into the system. The modulator valves just exhaust it when needed. All air for the service brakes is supplied by either the foot or hand valves. Besides, trailer ABS operates 100% independent of the tractor. All the tractor does is supply 12 volt constant power on the center pin of the 7 way cord to the trailer ABS module. If the trailer ABS module doesn't get power from the tractor, the system simply reverts to non-ABS brakes.

 

Now you said all trailer brakes were smoking EXCEPT the converter dolly? Does the converter dolly have spring brakes? If it doesn't, I'd be chasing a tractor supply pressure issue.

 

Sounds like your tractor protection valve maybe hanging up. It would be the valve your trailer hoses thread into.
Unless your truck has Automatic Traction Control/ Roll Stabilty System/ABS. Then it could be the RSS trailer brake activation valve. Your mechanic needs to look for a valve mounted on the frame down by the transmission it should allow air back to the tractor protection valve from the foot valve/hand valve. It will also have a tank air line attached to it and a wire harness to run it.
I have see also where the tractor ECM has been bad and will apply the brakes when hitting rough spots in the road. (But I haven’t seen the ecm drag the brakes)

 

You might want to check this out too! Over 18,000 Freightliners recalled for brake issue