Comprehensive Component Monitor (CCM)
The CCM is an on board strategy designed to monitor a concern in any electronic component or circuit that provides an input or output signal to the powertrain control module (PCM) and is not exclusively monitored by another monitor system. Inputs and outputs are considered inoperative when a concern exists due to a lack of circuit continuity, out-of-range value, or a failed rationality check.
The CCM covers many components and the related 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 carried out continuously. These tests may require the monitoring of several components and may only be carried out 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 is the injection control system.
In general, the CCM covers a broad range of individual component and circuit checks, and testing is carried out under various conditions. The CCM is enabled after the ignition switch is turned on for 3 seconds and the malfunction indicator lamp (MIL) is activated if the concern detected affects emissions. All of the CCM tests are also carried out during the 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.
- The input components monitored include the engine oil temperature (EOT), accelerator pedal position (APP), and camshaft position (CMP).
- The output components monitored include the injection pressure regulator (IPR) and exhaust gas recirculation (EGR) valve.
- The MIL is activated after a concern is detected if the concern detected affects emissions.