Failed to Communicate with Transmission Control Unit
The engine control module can’t communicate with the transmission control unit.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The engine computer is trying to check with the transmission computer but isn’t getting any response, which usually means there’s a communication error between the two devices.
What the computer is actually seeing
The engine control module (ECM) is expecting a signal from the transmission control module (TCM) within a certain time frame (usually in milliseconds) but isn’t receiving anything back, or the signal is not within the specified range.
What a healthy reading looks like
The ECM expects a response from the TCM within 200 ms after a request is sent. Voltage levels should be between 0.5V to 5.0V depending on whether the TCM is active.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Check wiring and connectors between ECM and TCM for damage or corrosion.
- 2Verify battery voltage is above 12.5 volts with engine off and 13.5-14.5 volts with engine running.
- 3Using a scan tool, check for other codes present that might indicate issues with the TCM.
- 4Inspect for proper voltage signals at the TCM connector; should be within expected ranges when key is on.
Common causes
- Faulty wiring or connectors between ECM and TCM
- Failed TCM
- ECM software issues or corruption
- Low battery voltage affecting communication
- Network issues in CAN bus system
Typical repair cost
$$-$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally drivable but you may notice shifting issues or reduced power due to the communication problem.
Will this code come back if I clear it?
It can, especially if the underlying issue isn’t fixed, like faulty wiring or a bad TCM.
Why does this code pair with other codes?
Communication issues often stem from multiple faults, such as wiring or control module failures, leading to several codes being triggered.
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