I am an in house tech for a food company and I really need some advice on this particular truck. The truck speed is very low as if the brakes were locked or the parking brake engaged, if you let go the accel pedal while driving it will come to a sudden stop it will not coast. I can hear the high speed contactor coming in as I press the pedal so I dont think theres any electrical issue also there is no error codes at all!!

I suspect the open differential is the culprit and I'll explain how I got to the conclusion: I jacked up the truck by the front end and left both wheels suspended and when I pressed the accelerator pedal both wheels started spinning in low speed instead of just one wheel spinning? I then did the same test to another identical truck and only one wheel spun and it did at high speed.

I then got into the faulty truck and drove it with the steering locked all the way to the left and pressed the accel pedal like driving in circles... to my surprise it reached top speed as if there were no issues... same result obtained when I locked the steering fully to the right...full speed!!

I might be wrong but this tells me there is no issues with the parking brake or service brakes being locked up or dragging, I can also see the parking brake engaging and releasing normally as requested.

Please help me out and if there's anyone with experience in this type of differentials let me know what should I do!! Thanks!!