The Transmission Control Module (TCM) controls the functions of this transmission. The TCM is part of a molded plastic lead frame module that is bolted to the mechatronic assembly. The lead frame module also has the Turbine Shaft Speed (TSS) sensor, Output Shaft Speed (OSS) sensor, Transmission Range (TR) sensor and Transmission Fluid Temperature (TFT) sensor integrated into it.

The TCM responds to inputs from the sensors and from the vehicle Controller Area Network (CAN) signal. The TCM uses the inputs to control the line pressure, shift and TCC solenoids. The TCM also provides power and ground for the reverse lamp relay coil and provides a PARK/NEUTRAL start enable signal.

The TCM uses the following input from the vehicle CAN signal:

Engine speed
Engine torque
Engine Coolant Temperature (ECT)
Engine Oil Temperature (EOT)
Throttle Position (TP)
Accelerator Pedal Position (APP)
Brake Pedal Position (BPP)
ABS wheel speed
Automatic Traction Control (ATC) status
Four-Wheel Drive (4WD) status

The TCM also:

monitors inputs and outputs for the presence of faults.
stores DTCs related to detected faults.
supplies output to the vehicle CAN for TR position, OSS , TSS , TFT , current gear and A/C inhibit.
provides On-Board Diagnostic (OBD) information using the CAN signal to illuminate the Malfunction Indicator Lamp (MIL) or Transmission Control Indicator Lamp (TCIL).
displays diagnostic information to a scan tool through the Data Link Connector (DLC).

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.

Safety Warning

Transmission Control Module (TCM): Notes

Use the Manual With the Right Hardware

When to See a Mechanic