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Powertrain Control Module

The PCM has a "learning" ability which allows it to make minor corrections for fuel system variations. PCM is mounted on top right front of engine. See Fig 1 . If battery power is interrupted, a vehicle performance change may be noticed. PCM module corrects itself, and normal performance returns if vehicle is allowed to "relearn" optimum control conditions. "Relearning" occurs when vehicle is driven at normal operating temperature under part throttle, moderate acceleration and idle conditions.

Fig 1: Locating ECT Sensor & PCM
G00028589Courtesy of GENERAL MOTORS CORP.