P0700 — Transmission Control System Malfunction
Seen on: Allison 3000/4000 series · Eaton Fuller
Transmission Control System Malfunction. Common causes: TCM fault, wiring issue, solenoid failure.
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
- TCM fault
- wiring issue
- solenoid failure
- Low trans fluid
- contaminated fluid
- valve body wear
FAQ
Transmission Control System Malfunction. Common causes: TCM fault, wiring issue, solenoid failure.
Serious — Power derate likely — plan to stop soon.
The most common cause is: TCM fault. Other possibilities include wiring issue; solenoid failure; Low trans fluid; contaminated fluid; valve body wear.
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.