Comprehensive Component Monitor
The comprehensive component monitor (CCM) is an on-board strategy designed to monitor a fault in any electronic component or circuit that provides input or output signal to the PCM and is not exclusively monitored by another monitor system. Inputs and outputs are considered inoperative when a failure exists due to a lack of circuit continuity, out-of-range value, or a failed rationality check.
The CCM covers many components and their circuits. The tests vary depending on the hardware, function, and type of signal. For example, analog inputs are typically checked for opens, shorts, out of range values and rationality. This type of monitoring is performed continuously. These tests may require the monitoring of several components and can only be performed under the appropriate test conditions. Some outputs are also monitored for the correct function by observing the reaction of the control system to a given change in the output command. An example of this would be the injection control system.
In general, the CCM covers a broad range of individual component and circuit checks and testing is performed under various conditions. The CCM is enabled after the ignition switch is turned on for three MIL is activated if the fault detected affects emissions. All of the CCM tests are also performed during on demand self-test.
The following is an example of some of the input and output components monitored by the CCM. The components monitored may belong to the engine, transmission or any other PCM supported subsystem.
- Inputs:
engine oil temperature (EOT), accelerator pedal position (APP), camshaft position (CMP)
- Outputs:
injection pressure regulator (IPR), exhaust gas recirculation (EGR) valve
- The MIL is activated after a fault is detected, if the fault detected affects emissions.