Toyota training course t852 engine control systems sec03

Technician Handbook 874 Engine Control Systems II 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 NOTE 42 The best source of the DTC setting parameter information is the Repair Manual specific to the vehicle Some parameters may not be outlined but should be assumed, i.e engine at operating temperature Carefully study the information to determine what must occur before a DTC will be recorded and how to diagnose the issue The DTC may be the result of an out-of-spec system monitor, not a component that has failed, and may be remedied with a new ECM calibration or upgrade Check for applicable Service Bulletins (SB) when diagnosing a malfunction detected by the comprehensive component monitor Technical Training Technician Handbook 874 Engine Control Systems II 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 Comprehensive Components Monitor Diagnosis Technical Training 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) 43 Technician Handbook 874 Engine Control Systems II 44 Technical Training ... information and look for applicable Service Bulletins (SB) 43 Technician Handbook 874 Engine Control Systems II 44 Technical Training ...Technician Handbook 874 Engine Control Systems II Mass Air Flow (MAF) Sensor Circuit There are two DTCs directly applicable to... position and engine speed The information in the image is from the P0100 and P0101 DTC troubleshooting sections of the Repair Manual Comprehensive Components Monitor Diagnosis Technical Training