Transmission Control Module (TCM) Malfunction
Indicates an issue with the communication or performance of the TCM.
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 Transmission Control Module is not working correctly, which can lead to shifting problems or the car not moving as expected.
What the computer is actually seeing
The TCM monitors inputs from various sensors and compares them to set parameters. When it detects a deviation or fails to communicate with the engine control module (ECM), it triggers the P1570 code.
What a healthy reading looks like
Voltage should be between 0.5V and 4.5V from the TCM inputs during operation, with appropriate readings from the throttle position sensor and vehicle speed sensor.
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.
- 11. Start by checking the wiring and connectors between the TCM and ECM for any signs of damage or corrosion. If damaged, repair or replace as necessary. Decision: Good wiring?
- 22. Inspect the transmission fluid level and condition. Ensure fluid is at the correct level and not burnt. Decision: Fluid good?
- 33. Test the voltage output from the TCM to the ECM. It should be within 0.5V to 4.5V. Use a multimeter. Decision: Voltage within spec?
- 44. If previous steps check out, check individual sensors related to the TCM, such as the throttle position and vehicle speed sensors. Test them for proper operation based on manufacturer specifications. Decision: Sensors functional?
Common causes
- Faulty Transmission Control Module (TCM)
- Wiring issues or corroded connectors between TCM and ECM
- Faulty or dirty transmission fluid
- Sensor failure (like throttle position sensor or vehicle speed sensor)
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not recommended to drive; the transmission may not shift properly, risking further damage.
Will this code come back after clearing it?
If the underlying issue isn't fixed, the code will likely return.
Why might this code appear alongside others?
This code can often relate to other TCM or transmission performance issues, so multiple codes can signal a larger problem.
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