Transmission Control Module (TCM) Fault
There is a fault in the transmission control module.
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 computer that controls the transmission isn't working right; it could be due to wiring problems, bad connectors, or the TCM itself failing.
What the computer is actually seeing
The TCM monitors input from various sensors (like speed and position sensors) and commands the transmission accordingly. A fault indicates it can't properly manage these inputs.
What a healthy reading looks like
Input voltages from sensors should be between 0.5V and 4.5V under normal operating conditions; TCM response time is typically under 100 milliseconds for shifts.
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 transmission fluid level; ensure it's within the specified range (typically 1/2" above the upper mark on the dipstick when hot).
- 2Inspect wiring and connectors to the TCM for any signs of damage or corrosion, ensuring tight connections.
- 3Use a scan tool to check for other related trouble codes; if multiple codes exist, address them based on severity and relevance.
- 4Test the TCM inputs: use a multimeter to verify sensor voltages are within normal range (0.5V - 4.5V). If out of spec, replace the faulty sensor.
- 5If all inputs are good and wiring is intact, replace the TCM.
Common causes
- Faulty transmission control module (TCM)
- Wiring issues or shorts in TCM harness
- Faulty transmission position sensor
- Low transmission fluid level
- Corroded or loose electrical connections
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It can be drivable, but shift quality may be poor; fix soon to avoid damage.
Will the code come back after clearing it?
If the root cause isn't fixed, yes, the code will likely return.
Why is this code related to shifting problems?
Because the TCM manages shifting based on sensor inputs; faults disrupt that operation.
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