874 Engine Control Systems II Technician Handbook Comprehensive Components Monitor Overview The comprehensive components composition parts monitor is used to monitor individual comp
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Comprehensive
Components
Monitor Overview
The comprehensive components (composition parts) monitor is
used to monitor individual components This monitor checks component circuits for opens, shorts, or performance issues If the component affects vehicle emissions but is not part of the other monitored systems, it is a comprehensive component The comprehensive components monitor is a continuous monitor
Many comprehensive components have two types of DTCs An open, a short, or no response is a one trip DTC A performance problem is usually a two trip DTC
An example of a comprehensive component is the MAF sensor If the ECM measures high or low voltage at the MAF sensor circuit when enabling conditions have been met, it will set an open or short DTC During normal operation, the MAF signal is roughly
proportional to engine load If this varies greatly, the ECM will set a signal performance DTC
Many comprehensive components exist on vehicles Most open, short, or performance DTCs are the result of the comprehensive component monitor
The best source of the DTC setting parameter information is the
NOTE
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Mass Air Flow (MAF)
Sensor Circuit
There are two DTCs directly applicable to the MAF circuit DTC P0100
is set when an open or short occurs in the MAF circuit It is a one trip DTC and has Fail-Safe strategy The Fail-Safe strategy fixes the ignition timing and the on time of the fuel injectors according to engine conditions
DTC P0101 has three different conditions to detect MAF sensor/circuit failure ECM is comparing the MAF signal against the expected MAF signal when compared to throttle position and engine speed
The information in the image is from the P0100 and P0101 DTC troubleshooting sections of the Repair Manual
Many comprehensive components exist on vehicles Most open, short,
or performance DTCs are the result of the comprehensive component monitor When trying to determine the cause of a circuit open, short, or performance issue, visually inspect the suspect component Check the Freeze Frame Data (FFD) and duplicate the conditions Use the Technical Information System (TIS) for Repair Manual (RM) and Electrical Wiring Diagram (EWD) information and look for applicable Service Bulletins (SB)
Comprehensive Components
Monitor Diagnosis
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