Engine Control Module: Description and Operation

The Powertrain Control Module (PCM) is the control center of the vehicle. It controls the following items:
^ Fuel metering system Transaxle/transmission shifting
^ Ignition timing
^ On-board diagnostics for powertrain functions

It constantly looks at the information from various sensors, and controls the systems that affect vehicle performance. The PCM also performs the diagnostic function of the system. It can recognize operational problems, alert the driver through the MIL, and store diagnostic trouble codes which identify the problem areas to aid the technician in making repairs.

The type of PCM used is a PCM 32U The knock sensor module is no longer a separate component. The PCM contains integrated knock sensor (KS) diagnostic circuitry. For more information on the integrated KS circuitry, refer to Knock Sensor (KS) System Description.

The PCM verifies that the password received from the VTD (Pass Key III(R)) Module via the Class 2 serial data line is correct. The VTD (Pass Key III(R)) Module can learn only one enable password. If the enable password is correct, the PCM enables the fuel system and engine starting system.

The PCM disables the fuel and starting systems if any of the following conditions occur:
^ The enable password incorrect.
^ The system disable password is sent by the VTD (Pass Key III(R)) Module.
^ No passwords are received - there is no communication with the VTD (Pass Key III(R)) Module.