Powertrain Control Module (PCM)

The Powertrain Control Module (PCM) is located on the lower left side of the Instrument Panel.

The PCM communicates with the Body Function Controller (BFC) via serial data over the Class 2 Serial Data Bus, circuit 1807. When the BFC has determined a Passed Theft condition, it sends a coded password to the PCM. Upon receipt of the correct password, the PCM enables the fuel injection system, allowing the vehicle to operate correctly. Please note, the PCM may allow the car to start and quickly stall during a Failed Theft condition.

The ways the PCM may enter a Tamper Mode state is by a bad timing cycle and an incorrect password.

If a password is not received from the BFC within a preset time window, the PCM will short a Short Tamper Mode during which the PCM will not allow the car to operate for 4 seconds. If the password is incorrect, the PCM will enter the Long Tamper Mode. In this mode, THEFT SYSTEM Indicator will flash and the Fuel Injectors will be shut off for approximately 10 minutes. Again, the vehicle may start, but the engine will quickly stall due to fuel cut-off.

In the event of an open in serial data communication between the BFC and the PCM, the PCM will become fail-enabled if the car has already Passed Theft for that ignition cycle (i.e. the engine is running) and may set Diagnostic Trouble Codes (DTC). In this event, the THEFT SYSTEM indicator will light continuously and the PCM will become fail-enabled for future ignition cycles. If a failure in serial data occurs before the ignition cycle, when the PCM is not fail-enabled, the PCM will never receive a valid password to enable continued use of the Fuel Injectors.