THEORY OF OPERATION
The Electronic Throttle Control (ETC) system uses two Accelerator Pedal Position (APP) Sensors to monitor the accelerator pedal position. The APP Sensors 1 and 2 are integrated into one assembly located at the pedal assembly. Each sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The Powertrain Control Module (PCM) reads the two signals individually and then compares the two signals as a redundant check of the throttle position. One of the sensors will fluctuate between 0 volts and 5.0 volts and the other sensor will fluctuate between 0 volts and 2.5 volts. The fluctuation of the two sensors should move proportionately. E.G. When operating properly, the voltage reading of the sensor operating on the 5.0 volt scale will always approximately two time the voltage reading of the sensor on the 2.5 volts scale.
The Electronic Throttle Control (ETC) system uses two Accelerator Pedal Position (APP) Sensors to monitor the accelerator pedal position. The APP Sensors 1 and 2 are integrated into one assembly located at the pedal assembly. Each sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The Powertrain Control Module (PCM) reads the two signals individually and then compares the two signals as a redundant check of the throttle position. One of the sensors will fluctuate between 0 volts and 5.0 volts and the other sensor will fluctuate between 0 volts and 2.5 volts. The fluctuation of the two sensors should move proportionately. E.G. When operating properly, the voltage reading of the sensor operating on the 5.0 volt scale will always approximately two time the voltage reading of the sensor on the 2.5 volts scale.
The Oxygen Sensors (O2 Sensor) are used for fuel control and catalyst monitoring. Each O2 Sensor measures the oxygen content of the exhaust stream. When the engine is started, the Powertrain Control Module (PCM) operates in an Open Loop mode, ignoring the O2 Sensor signal voltage while calculating the air-to-fuel ratio. The heating elements inside each O2 Sensor heats the sensor to bring it to operating conditions faster. This allows the system to enter Closed Loop earlier and the PCM to calculate the air-to-fuel ratio sooner. While the engine runs, the O2 Sensor heats up and begins to generate a voltage within a range of 0-1, 275 mV. Once sufficient O2 Sensor voltage fluctuation is observed by the PCM, Closed Loop is entered. The PCM uses the O2 Sensor voltage to determine the air-to-fuel ratio. An O2 Sensor voltage that increases toward 1, 000 mV indicates a rich fuel mixture. An O2 Sensor voltage that decreases toward 0 mV indicates a lean fuel mixture. The Powertrain Control Module (PCM) makes short term and long term fuel corrections to maintain stoichiometric fuel/air ratio for best catalytic converter efficiency. Short term fuel correction is based on upstream O2 Sensor output and is designed for quick engine response. The long term fuel correction compensated for variations in the engine specifications, sensor tolerances and component aging and is designed to correct rich and lean conditions over a longer period of time.
For an aged O2 Sensor, the response rate to the air/fuel change is slower than when it was new. The O2 Sensor tends to move less with the same air/fuel changes in a given time frame. Therefore by observing the activity of voltage readings from the upstream O2 Sensor, the quality of the O2 Sensor can be detected.
The Oxygen Sensors (O2 Sensor) are used for fuel control and catalyst monitoring. Each O2 Sensor measures the oxygen content of the exhaust stream. When the engine is started, the Powertrain Control Module (PCM) operates in an Open Loop mode, ignoring the O2 Sensor signal voltage while calculating the air-to-fuel ratio. The heating elements inside each O2 Sensor heats the sensor to bring it to operating conditions faster. This allows the system to enter Closed Loop earlier and the PCM to calculate the air-to-fuel ratio sooner. While the engine runs, the O2 Sensor heats up and begins to generate a voltage within a range of 0-1, 275 mV. Once sufficient O2 Sensor voltage fluctuation is observed by the PCM, Closed Loop is entered. The PCM uses the O2 Sensor voltage to determine the air-to-fuel ratio. An O2 Sensor voltage that increases toward 1, 000 mV indicates a rich fuel mixture. An O2 Sensor voltage that decreases toward 0 mV indicates a lean fuel mixture. The Powertrain Control Module (PCM) makes short term and long term fuel corrections to maintain stoichiometric fuel/air ratio for best catalytic converter efficiency. Short term fuel correction is based on upstream O2 Sensor output and is designed for quick engine response. The long term fuel correction compensated for variations in the engine specifications, sensor tolerances and component aging and is designed to correct rich and lean conditions over a longer period of time.
For an aged O2 Sensor, the response rate to the air/fuel change is slower than when it was new. The O2 Sensor tends to move less with the same air/fuel changes in a given time frame. Therefore by observing the activity of voltage readings from the upstream O2 Sensor, the quality of the O2 Sensor can be detected.
For an aged Upstream O2 Sensor, the response rate to the air/fuel change is slower than when it was new. The O2 Sensor tends to move less with the same air/fuel changes in a given time frame. Therefore by observing the activity of voltage readings from the Upstream O2 Sensor, the quality of the O2 Sensor can be detected. The Downstream O2 Sensor is located in the exhaust path behind the Catalytic Converter, and is monitored for proper response to assure optimum Catalytic Converter efficiency. The Downstream O2 Sensor response monitor is intended to diagnose a Downstream O2 Sensor that is not moving or stuck in a voltage window and to insure accurate information for catalyst monitor diagnosis.
The primary winding of each coil-on-plug Ignition Coil is supplied power via the Fused Automatic Shut Down (ASD) Relay Output circuit. The Powertrain Control Module (PCM) completes the circuit to ground internally (low side driver) allowing the energy that is stored in the magnetic field of the primary coil to be transferred to the spark plug via the secondary coil. The PCM determines spark timing by monitoring engine operating parameters via various sensors and then calculating the appropriate moment to initiate the spark event. The PCM manages spark advance depending on engine RPM, manifold absolute pressure, engine coolant and oil temperature.
The primary winding of each coil-on-plug Ignition Coil is supplied power via the Fused Automatic Shut Down (ASD) Relay Output circuit. The Powertrain Control Module (PCM) completes the circuit to ground internally (low side driver) allowing the energy that is stored in the magnetic field of the primary coil to be transferred to the spark plug via the secondary coil. The PCM determines spark timing by monitoring engine operating parameters via various sensors and then calculating the appropriate moment to initiate the spark event. The PCM manages spark advance depending on engine RPM, manifold absolute pressure, engine coolant and oil temperature.
The primary winding of each coil-on-plug Ignition Coil is supplied power via the Fused Automatic Shut Down (ASD) Relay Output circuit. The Powertrain Control Module (PCM) completes the circuit to ground internally (low side driver) allowing the energy that is stored in the magnetic field of the primary coil to be transferred to the spark plug via the secondary coil. The PCM determines spark timing by monitoring engine operating parameters via various sensors and then calculating the appropriate moment to initiate the spark event. The PCM manages spark advance depending on engine RPM, manifold absolute pressure, engine coolant and oil temperature.
The primary winding of each coil-on-plug Ignition Coil is supplied power via the Fused Automatic Shut Down (ASD) Relay Output circuit. The Powertrain Control Module (PCM) completes the circuit to ground internally (low side driver) allowing the energy that is stored in the magnetic field of the primary coil to be transferred to the spark plug via the secondary coil. The PCM determines spark timing by monitoring engine operating parameters via various sensors and then calculating the appropriate moment to initiate the spark event. The PCM manages spark advance depending on engine RPM, manifold absolute pressure, engine coolant and oil temperature.
The fuel level signal is a direct input to the Cluster. The fuel level signal is sent to the Totally Integrated Power Module (TIPM) over the CAN B bus circuit. The Powertrain Control Module (PCM) receives the fuel level signal from the TIPM over the CAN C bus circuit.
The ambient temperature sensor signal is a direct input to the Totally Integrated Power Module (TIPM). The TIPM sends the Powertrain Control Module (PCM) the ambient temperature signal over the CAN C bus.
The Powertrain Control Module (PCM) receives the vehicle speed signal over the CAN C bus from the Anti-lock Brake Module.
The A/C Pressure Transducer signal is a direct input to the Totally Integrated Power Module (TIPM). The TIPM sends the Powertrain Control Module (PCM) the A/C pressure signal over the CAN C bus.
The Powertrain Control Module (PCM) receives the vehicle speed signal over the CAN C bus from the Anti-lock Brake Module.
The Totally Integrated Power Module (TIPM) receives a fuel level signal over CAN B from the Cluster. The TIPM transmits the fuel level message to the PCM over the CAN C bus.
The ABS Module sends vehicle speed information over the CAN C Bus circuit to the Powertrain Control Module (PCM).
The Anti-Lock Brake (ABS) Module sends an implausible distance signal over the CAN C Bus circuit to the Powertrain Control Module (PCM).
The ABS Module sends an implausible distance signal over the CAN C Bus circuit to the Powertrain Control Module (PCM).