U0101 — Lost Communication with TCM
Seen on: All trucks with automatic trans
Lost Communication with TCM. Common causes: TCM power loss, CAN wiring fault.
Look up listed providers near you and give them this code when you call.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- TCM power loss
- CAN wiring fault
- J1939 terminator missing
- TCM failure
FAQ
Lost Communication with TCM. Common causes: TCM power loss, CAN wiring fault.
Serious — Power derate likely — plan to stop soon.
The most common cause is: TCM power loss. Other possibilities include CAN wiring fault; J1939 terminator missing; TCM failure.
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.