Scheme 35
For a complete wiring diagram, refer to appropriate SYSTEM WIRING DIAGRAMS article .
THEORY OF OPERATION
Dual Variable Valve Timing (VVT) allows the Powertrain Control Module (PCM) to monitor and adjust the position of each camshaft, based on desired torque levels and engine operating conditions. The PCM controls two solenoid operated control valves, one for each camshaft, that are used to direct oil pressure to hydraulic actuators mounted between each camshaft and its driving sprocket. The oil pressure alters the angular position or phasing of each camshaft relative to crankshaft rotation. A sensor is used to monitor the position of each camshaft.
Dual Variable Valve Timing (VVT) allows the PCM to monitor and adjust the position of each camshaft, based on desired torque levels and engine operating conditions. The PCM controls two solenoid operated control valves, one for each camshaft, that are used to direct oil pressure to hydraulic actuators mounted between each camshaft and its driving sprocket. The oil pressure alters the angular position or phasing of each camshaft relative to crankshaft rotation. A sensor is used to monitor the position of each camshaft.
Ambient Air Temperature (AAT) sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. The AAT reading is a bussed message from the Totally Integrated Power Module (TIPM) to the Powertrain Control Module (PCM). Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors are compared. The AAT sensor is a variable resistor that measures the ambient air temperature. The TIPM supplies a 5 Volt reference and a ground to the sensors low reference signal circuit. When the AAT is low, the sensor resistance is high. When the AAT is high, the sensor resistance is low.
Ambient Air Temperature (AAT) sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. The AAT reading is a bussed message from the Totally Integrated Power Module (TIPM) to the Powertrain Control Module (PCM). Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors are compared. The AAT sensor is a variable resistor that measures the ambient air temperature. The TIPM supplies a 5 Volt reference and a ground to the sensors low reference signal circuit. When the AAT is low, the sensor resistance is high. When the AAT is high, the sensor resistance is low.
Ambient Air Temperature (AAT) sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. The AAT reading is a bussed message from the Totally Integrated Power Module (TIPM) to the Powertrain Control Module (PCM). Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors are compared. The AAT sensor is a variable resistor that measures the ambient air temperature. The TIPM supplies a 5 Volt reference and a ground to the sensors low reference signal circuit. When the AAT is low, the sensor resistance is high. When the AAT is high, the sensor resistance is low.
The Manifold Absolute Pressure (MAP) sensor is a transducer that varies resistance according to changes in altitude and atmospheric conditions. The MAP reading gives the Powertrain Control Module (PCM) an indication of the current air pressure within the intake manifold. The PCM uses this information to calculate fuel delivery. The MAP sensor has a 5 Volt reference circuit, a low reference circuit and a signal circuit. The PCM supplies 5 Volts to the MAP sensor on a 5 Volt reference circuit and provides a ground on a low reference circuit. The MAP sensor provides a voltage signal to the PCM on a signal circuit relative to the pressure changes.
The Manifold Absolute Pressure (MAP) sensor is a transducer that varies resistance according to changes in altitude and atmospheric conditions. The MAP reading gives the Powertrain Control Module (PCM) an indication of the current air pressure within the intake manifold. The PCM uses this information to calculate fuel delivery. The MAP sensor has a 5 Volt reference circuit, a low reference circuit and a signal circuit. The PCM supplies 5 Volts to the MAP sensor on a 5 Volt reference circuit and provides a ground on a low reference circuit. The MAP sensor provides a voltage signal to the PCM on a signal circuit relative to the pressure changes.
Intake Air Temperature Sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors will be compared. If the engine coolant and ambient air temperature sensors agree and the intake air temperature does not agree, the intake air temperature sensor is declared as irrational. If declared irrational a second comparison will be done after a short drive cycle.
Intake Air Temperature Sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors will be compared. If the engine coolant and ambient air temperature sensors agree and the intake air temperature does not agree, the intake air temperature sensor is declared as irrational. If declared irrational a second comparison will be done after a short drive cycle.
Intake Air Temperature Sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors will be compared. If the engine coolant and ambient air temperature sensors agree and the intake air temperature does not agree, the intake air temperature sensor is declared as irrational. If declared irrational a second comparison will be done after a short drive cycle.
Intake Air Temperature Sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors will be compared. If the engine coolant and ambient air temperature sensors agree and the intake air temperature does not agree, the intake air temperature sensor is declared as irrational. If declared irrational a second comparison will be done after a short drive cycle.
Intake Air Temperature Sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors will be compared. If the engine coolant and ambient air temperature sensors agree and the intake air temperature does not agree, the intake air temperature sensor is declared as irrational. If declared irrational a second comparison will be done after a short drive cycle.
Intake Air Temperature Sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors will be compared. If the engine coolant and ambient air temperature sensors agree and the intake air temperature does not agree, the intake air temperature sensor is declared as irrational. If declared irrational a second comparison will be done after a short drive cycle.
The Powertrain Control Module (PCM) performs a continuous check of the O2 sensor heater circuit during operation. The heater circuit is momentarily disabled to allow a resistance measurement to be taken to infer heater temperature. The current delivery to the heater is duty cycled to maintain a specific target temperature. The error from the target temperature is continuously monitored to assess heater performance.
The Powertrain Control Module (PCM) performs a continuous check of the O2 sensor heater circuit during operation. The heater circuit is momentarily disabled to allow a resistance measurement to be taken to infer heater temperature. The current delivery to the heater is duty cycled to maintain a specific target temperature. The error from the target temperature is continuously monitored to assess heater performance.
The fuel feedback system will maintain a stoiciometric fuel/air mixture, 14.7:1, by modifying the injector pulsewidth according to the oxygen content of the exhaust gas. The Powertrain Control Module (PCM) makes short term and long term fuel corrections to maintain stoiciometric 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.
The fuel feedback system will maintain a stoiciometric fuel/air mixture, 14.7:1, by modifying the injector pulsewidth according to the oxygen content of the exhaust gas. The Powertrain Control Module (PCM) makes short term and long term fuel corrections to maintain stoiciometric 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.
The Powertrain Control Module (PCM) compares Engine Coolant Temperature (ECT), Intake Air Temperature (IAT), and Ambient Air Temperature (AAT) under cold start conditions. Following a start to run delay time, the sensor values are compared. If the one sensor value is not within a specified range of the other two sensors, the value is determined to be irrational. Once the general temperature rationality is passed, the PCM determines that the general temperature sensor values are correct. The PCM compares the Oil Temperature Sensor value to a threshold based on the other temp sensor values. If the difference is greater than a calibrated value, the diagnostic fails.
This DTC will set to indicate an overheating transmission or engine cooling system. Extended transmission operation above 115° C (240° F) will reduce the durability of the transmission and should be avoided. Correcting the cooling system operation or installing an additional transmission oil cooler will improve transmission durability, especially under extreme conditions such as city/construction stop and go traffic, trailer towing, aggressive driving in low gear, or operation in mountainous areas.