Powertrain Control Module: Notes

For exact location of Powertrain Control Module (PCM), see PCM LOCATION in appropriate SELF-DIAGNOSTICS article or COMPONENT LOCATIONS in appropriate SYSTEM & COMPONENT TESTING article. On some models, the PCM may be referred to as an Electronic Control Module (ECM). Although the 2 units may process different signals, the 2 terms are interchangeable.

The PCM contains the Arithmetic Logic Unit (ALU), Central Processing Unit (CPU), power supply and system memories. The PCM has a "learning" ability which allows it to make minor corrections for fuel system variations. If battery power to PCM is interrupted, a vehicle performance change may be noticed. This will correct itself and normal performance will return if vehicle is allowed to "relearn" optimum control conditions. This is accomplished by driving vehicle at normal operating temperature, under part throttle, moderate acceleration and idle conditions.