What it means
The Transmission Control Module communication circuit reports a communication circuit range/performance fault. Data exchange between TCM and ECM is impaired.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The Transmission Control Module (TCM) exchanges transmission data with the Engine Control Module (ECM) over the vehicle network. This code sets when the communication circuit's performance or signal behavior falls outside the expected range, even if messages are not completely lost.
Common causes
Most likely first.
- Communication bus fault
- TCM internal fault
- Gateway module routing CAN messages incorrectly
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Save freeze-frame data and scan all modules for TCM communication or network performance codes.
- Review live network status and TCM data for delayed, intermittent, or implausible messages between the TCM and ECM.
- Inspect TCM connectors and network wiring for loose pins, corrosion, chafing, or water damage that could cause intermittent communication.
- Check TCM power and ground connections and the vehicle battery condition for interruptions that could degrade messages.
- Test network signal quality and gateway routing using the manufacturer's procedure if the basic checks do not reveal the fault.
Common fixes
- Clean and secure a loose or corroded TCM connector.
- Repair damaged or intermittently connected network wiring.
- Repair poor TCM power or ground connections.
- Correct gateway routing or configuration if it causes out-of-range message performance.
- Repair or replace the TCM if testing confirms an internal communication fault.
Can I keep driving?
Because intermittent or poor TCM communication can cause unpredictable shifting or limp mode, avoid long journeys and hard acceleration until diagnosed. Stop if shifts become erratic or the vehicle loses drive.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.