Powertrain Control Module Description: Notes

Fig 1: Data Link Connector And PCM

Courtesy of GENERAL MOTORS CORP.

The powertrain control module (PCM) is a precision 32-bit microprocessor and is an essential part of the electronic control system. The PCM is responsible for such major functions as control of the fuel injectors, the idle air control (IAC) valve, the fuel pump relay, etc. The PCM (1) is located below the instrument panel (IP) storage compartment. Communication with the PCM is through the data link connector (2) located on the left side below the IP.

The PCM performs the OBD II diagnostic tests of the emission related systems. The PCM supplies a buffered voltage, called reference voltage, to the various information sensors and switches. The PCM controls most components with an electronic switch that completes a ground circuit when turned ON. The electronic switch is commonly referred to as an output driver. The PCM is also responsible for a self-diagnosis function and a fail-safe function.