Automatic Transmission Control Module (ATCM)

The ATCM receives information from various input devices and uses this information to control No. 1, No. 2 and lock-up solenoids. The ATCM contains a self-diagnostic system, which will store fault code if failure or problem exists in the electronic control system. Fault code can be retrieved to determine transmission problem area. See SELF-DIAGNOSTIC SYSTEM  . The ATCM is located near center console. See Fig 1 .

Fig 1: ATCM, OD & Pattern Select Switch

Courtesy of GENERAL MOTORS CORP.

Fig 2: ECT Indicator & OD OFF Lights

Courtesy of GENERAL MOTORS CORP.