Comprehensive Component Monitor

DESCRIPTION
The Comprehensive Component Monitor is a self-test strategy within the Powertrain Control Module (PCM) that detects malfunctions of any electronic powertrain component/system providing input to the PCM and is not exclusively an input to any other OBD II monitor.

Hardware
Inputs monitored include the Vehicle Speed (VSS), Mass Air Flow (MAF), Engine Coolant Temperature (ECT) and Throttle Position (TP) sensors.

Outputs monitored include the ignition system (includes ID and PIP), fuel pump, fan control, idle speed control and transmission controls.

Operation
Input components are considered malfunctioning if there is lack of continuity, or if the input signal is out of range or not in proper relationship to signals it is compared against (this is called a rationality check).

Output components are considered malfunctioning if there is lack of continuity or if an expected output response to a PCM command does not occur.

DTCs and MIL Operation
When a malfunction has been present for two drive cycles, the DTC is stored in the PCM and the MIL is turned On. The MIL is turned Off after three consecutive trips without the same malfunction being detected provided no other DTCs are stored that would independently turn the MIL On. The DTC will be erased from memory after 40 warm-up cycles without the malfunction being detected after the MIL is turned Off. Another method of erasing the DTC is initiating a Powertrain Control Module Reset.