U0103 — Lost Communication with Gear Shift Module
Seen on: Heavy Truck
Lost Communication with Gear Shift Module. Common causes: Shift module not on CAN.
Your code rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Shift module not on CAN
- Shift module power/ground fault
- CAN fault
First moves (roadside)
- Check shift selector power and CAN connections
FAQ
Lost Communication with Gear Shift Module. Common causes: Shift module not on CAN.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Shift module not on CAN. Other possibilities include Shift module power/ground fault; CAN fault.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.