Transmission Control Module

DESCRIPTION 

Courtesy of CHRYSLER GROUP, LLC

On 8HP75/850RE equipped vehicles, the transmission valve body includes the TCM, all solenoids and sensors, and can be referred to as the 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 need to be replaced, the complete TCMA (valve body) must be replaced.

OPERATION FOR 8HP75/850RE TCM 

Courtesy of CHRYSLER GROUP, LLC

1 - Solenoid A

2 - Solenoid D

3 - Solenoid B

4 - Solenoid E

5 - Solenoid C

6 - Torque Converter Control (TCC) Solenoid

7 - Line Pressure Solenoid

8 - Park Release Solenoid

9 - Park Hold Mechanical Solenoid

10 - Park Release Mechanical Valve

Courtesy of CHRYSLER GROUP, LLC

1 - Input Speed Sensor (ISS)

2 - TCM (Includes Transmission Temperature Sensor)

3 - External Wire Harness Connector

4 - Output Speed Sensor (OSS)

5 - Park Position Sensor

The valve body, which includes the TCM, controls the delivery and pressure of transmission fluid. The TCM is integral to the valve body. The TCM regulates the amount of hydraulic pressure used to engage the clutches and the 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) signal from the Antilock Brake System (ABS) module.

If the TCMA is replaced, it must  be programmed and a drive learn needs to be performed before returning the vehicle to the customer.