VOLVO VNL 630 2016 - 2nd trailer brakes overheating(is it my truck or is it jb hunt trailers?)

If it was all 4 brakes on both trailers and you hooked on to the 2nd one right after the first then I'd be looking at the truck. I'd be checking to see if your truck is properly venting the service line whenever you let your foot off the brake pedal. Easy enough way to check that. With a trailer attached Just chock your wheels on flat ground, release the brakes, then step on the brake pedal hard and release. Then go out and remove the service gladhand from the trailer. If you get a burst of air out of the service gladhand then your truck has an issue.

Stupid question but you didn't have the trailer spike stuck partially activated? Have seen guys hang stuff off the handle and drag trailer brakes before.

 

Volvo has advanced braking system to control brake air pressure to truck vs trailer. They use rear truck airbag pressure to determine is truck loaded or bobtail to distribute brake power between trailer and truck.
Bobtail air pressure has to be calibrated in ABS/ESP truck module. Acom Diagnostic can be used.
Faulty valve can cause what you have. Really PITA situation because no faulty codes set and in case you have situation to apply hard brake trailer wheels will lock then released by trailer ABS and you don't have almost any brakes on the truck at this moment even brake pedal depressed all the way down.

 

AModelCat said: I'd be checking to see if your truck is properly venting the service line whenever you let your foot off the brake pedal.
"I stopped and noticed there was some air pressure on the blue gladhand. What could this be?"
Quick Release Valve

 

Should be under the cab at the rear of the tractor. The air hoses for the trailer usually connect to it. Don't forget the thumbs up next to reply.


Here's an actual pic from another posting. The QR valve is between the white and orange threads.