Have a similar question in the transmission forum as I am not sure where the problem is. I am unable to go in reverse sometimes. It will shift into R and D and when in R the engine labours but the truck will not move. It moves ok in forward direction. Can my brakes be jamming?

Thanks

 

I also answered in the transmission section to close the thread. Had it trailered to the dealer (400 km and 1 week) turns out it was the parking brake had fallen apart and all the parts were silently floating around in there. Then when in reverse they would jam. They repaired that under warranty but soaked me 600 for front brakes.