Transmission Control Module

WARNING: This page is about a different car, the 2018 GMC Yukon XL, 2018 GMC Yukon, 2018 Chevrolet Tahoe, 2018 Cadillac Escalade ESV, and 2018 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Transmission Control Module

Courtesy of GENERAL MOTORS COMPANY

The Transmission Control Module (TCM) for this transmission is a remotely mounted - stand-alone controller. The TCM has one 66 way connector to interface with vehicle electrical system, transmission assembly and other vehicle control modules. The TCM receives and sends various input and output signals from a number of switches and sensors within the transmission and throughout the vehicle. In addition, the TCM is part of a network of other control modules on the vehicle. This network of control modules will share information with each other, over a common serial data communications line. Based upon the TCM software/calibrations and input information the TCM receives, it will always have final authority of when to allow an upshift or downshift whether in manual mode operation or in drive position for automatic shifting.