Overview:
Fault Code 35 indicates the transmission failed to communicate with the engine over the J1939 data link.

Detection:
Starting 75 seconds after key on and throughout the operation, the Shift Controller constantly communicates with the engine ECM. If communication fails for more than 5 seconds, Fault Code 35 is set.

Fallback:
If the fault occurs while moving, it causes a current gear fallback. Once vehicle has stopped, the starting gear and reverse can be engaged. If the failure occurs at system initialization, it causes an AutoSelect fallback mode.

Possible Causes:
1) J1939 data link
2) Engine ECM
3) Vehicle Harness or Connections
4) Engine Harness or Connections
5) Excessive radio interference
6) Shift Controller

Shop Talk:
Key on. If the fault is present, the system should automatically detect the problem and set the code. If the fault is not present at key on, operate the vehicle and attempt to duplicate the driving conditions that triggered the fault code. Possible triggers include heat, vibration, and varying levels of throttle demand. It may take up to 75 seconds to set this fault.