Data Link - Transmission Control Module (TCM)
Transmission Control Module not communicating correctly.
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 control module (ECM) is having a hard time talking to the transmission control module. This can make the transmission act erratically or not shift properly.
What the computer is actually seeing
The ECM expects to receive valid data signals from the TCM every 100 ms. If it doesn’t receive a signal within 200 ms, it logs a fault code.
What a healthy reading looks like
The TCM should respond with data within 100 ms. Voltage signals should be between 0.5V and 4.5V depending on shift conditions, with CAN communication rates typically at 250 Kbps.
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 the transmission fluid level; it should be within the proper range. If low, top it off and retest.
- 2Inspect wiring and connectors for any signs of damage or corrosion. Repair as necessary.
- 3Verify the TCM's ground connections. Resistance should be less than 5 ohms.
- 4Use a scan tool to check if the TCM communicates with the ECM. If no communication, the TCM might be faulty; otherwise, continue diagnosis.
Common causes
- Faulty transmission control module
- Damaged wiring or connectors in the transmission circuit
- Poor ground connection to the TCM
- Low transmission fluid levels
Typical repair cost
$$
Related codes
Frequently asked questions
Can I still drive my vehicle with this code?
Yes, but expect shifting issues. It's best to fix it soon to prevent further damage.
Will this code come back after I clear it?
If the underlying issue isn't fixed, yes, it will likely return.
Why is this code showing with others?
These codes are often linked to similar communication issues between modules.
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