Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Transmission Control Module - 8HP45/8HP70
The Transmission Control Module (TCM), or Transmission Control Module Assembly (TCMA) is extremely sensitive to Electrostatic Discharge (ESD). Always use a ground strap and follow the ESD guidelines in ELECTROSTATIC DISCHARGE SENSITIVE DEVICES. Failure to follow these instructions may result in damage to the TCM/TCMA.
The valve body includes the Transmission Control Module (TCM), all solenoids and sensors, and can be referred to as the Transmission Control Module Assembly (TCMA). The TCM is attached to the valve body between the transmission case and the valve body. If any component of the valve body including the TCM sensors or solenoids needs to be replaced, the complete TCMA (valve body) must be replaced. For further information of the TCMA, refer to 8HP50/850RE, VALVE BODY, DESCRIPTION or 8HP70, VALVE BODY, DESCRIPTION .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.