Transmission Control Module (TCM) 8-Speed
DESCRIPTION
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 VALVE BODY, DESCRIPTION AND OPERATION .
OPERATION
| 1 - Solenoid A |
| 2- Solenoid D |
| 3 - Solenoid B |
| 4 - Solenoid E |
| 5 - Solenoid C |
| 6 - TCC Solenoid |
| 7 - Line Pressure Solenoid |
| 8 - Park Release Solenoid |
| 9 - Park Hold Mechanical Solenoid |
| 10 - Park Release Mechanical Valve |
| 1 - Input Speed Sensor |
| 2 - TCM (Includes Transmission Temperature Sensor) |
| 3 - External Wire Harness Connector |
| 4 - Output Speed Sensor |
| 5 - Park Position Sensor |
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, which includes the Transmission Control Module (TCM), controls the delivery and pressure of transmission fluid. The TCM is integrated into the valve body. The TCM regulates the amount of hydraulic pressure used to engage the clutches and the Torque Converter Clutch (TCC), in addition to directing hydraulic pressure to engage or release any given clutch for any given required gear. The TCM will actuate the valves via solenoids based on the position of the shifter, transmission fluid temperature, engine operating conditions, traction conditions and driver demands. During a shift, the TCM will actuate the solenoids to match the gear ranges to the optimal torque range of the engine based on the position of the accelerator pedal, shifter and vehicle speed as determined by the Powertrain Control Module (PCM) based on input from the Vehicle Speed Sensor (VSS) and Antilock Brake System (ABS) module. Due to the complexity of the transmission control system, always refer to the transmission electrical/electronic diagnostics in this article when attempting to diagnose transmission problems.
If the Transmission Control Module Assembly (TCMA) is replaced, it must be programmed and a drive learn needs to be performed before returning the vehicle to the customer for programming and drive learn procedures. Refer to VERIFICATION-8-SPEED .