THEORY OF OPERATION
The Fuel Level Sensor information is a bussed message to the Powertrain Control Module (PCM) from the Body Control Module (BCM). The fuel level rationality will set a fault for a fuel level reading that does not change over an accumulated mileage threshold to keep stuck high or stuck low fuel levels from disabling OBD monitors. If the vehicle is fitted with a saddle tank fuel system this feature includes diagnostics for both of the sending units and diagnostics for a siphon tube that has become disconnected or plugged. The power up test looks to see a large enough fuel level voltage change from the last key-off to the following engine run. The engine run test looks to see a fuel level voltage change over an accumulated mileage.
Vehicles fitted with saddle fuel tank configurations have two Fuel Level Sensors. The primary side of the tank has the filler tube inlet near the bottom and contains the Fuel Pump Module. During fuel tank fills, fuel must overflow the primary side to reach the secondary side of the tank. As fuel is consumed, a siphon tube is used to draw fuel from the secondary side to the primary side. Because the siphon tube flow rate exceeds the fuel consumption rate, the secondary side of the tank will be empty before fuel is depleted from the primary side. Fuel Level Sensor 1 is located on the primary side of the tank. Fuel Level Sensor 2 is located on the secondary side of the tank.
The Fuel Level Sensor information is a bussed message to the Powertrain Control Module (PCM) from the Body Control Module (BCM). The fuel level rationality will set a fault for a fuel level reading that does not change over an accumulated mileage threshold to keep stuck high or stuck low fuel levels from disabling OBD monitors. If the vehicle is fitted with a saddle tank fuel system this feature includes diagnostics for both of the sending units and diagnostics for a siphon tube that has become disconnected or plugged. The power up test looks to see a large enough fuel level voltage change from the last key-off to the following engine run. The engine run test looks to see a fuel level voltage change over an accumulated mileage.
Vehicles fitted with saddle fuel tank configurations have two Fuel Level Sensors. The primary side of the tank has the filler tube inlet near the bottom and contains the Fuel Pump Module. During fuel tank fills, fuel must overflow the primary side to reach the secondary side of the tank. As fuel is consumed, a siphon tube is used to draw fuel from the secondary side to the primary side. Because the siphon tube flow rate exceeds the fuel consumption rate, the secondary side of the tank will be empty before fuel is depleted from the primary side. Fuel Level Sensor 1 is located on the primary side of the tank. Fuel Level Sensor 2 is located on the secondary side of the tank.
The Radiator Fan Module is a smart device which controls the PCM Radiator Fan speed. The Radiator Fan Module receives a continuous wake-up signal from the Radiator Fan Relay output. The Powertrain Control Module (PCM) controls the Radiator Fan Relay via a LSD to close the relay an turn on the wake-up signal. The PCM communicates with the Radiator Fan Module through a Pulse-Width Modulated (PWM) signal. The PCM communicates the desired fan speed using the PWM circuit. The PWM Radiator Fan can be operated between 10% duty cycle (Low speed) and 92% duty cycle (High speed). The Radiator Fan Module relays internal fault messages to the PCM using the same PWM circuit.
If the wake-up signal between the Radiator Fan Relay and the Radiator Fan Module is lost after Radiator Fan Module is initialized, the fan defaults to high speed.
The Radiator Fan Module is a smart device which controls the PCM Radiator Fan speed. The Radiator Fan Module receives a continuous wake-up signal from the Radiator Fan Relay output. The Powertrain Control Module (PCM) controls the Radiator Fan Relay via a LSD to close the relay an turn on the wake-up signal. The PCM communicates with the Radiator Fan Module through a Pulse-Width Modulated (PWM) signal. The PCM communicates the desired fan speed using the PWM circuit. The PWM Radiator Fan can be operated between 10% duty cycle (Low speed) and 92% duty cycle (High speed). The Radiator Fan Module relays internal fault messages to the PCM using the same PWM circuit.
If the wake-up signal between the Radiator Fan Relay and the Radiator Fan Module is lost after Radiator Fan Module is initialized, the fan defaults to high speed.
The vehicle speed sensor rationality is a continuous test that monitors the vehicle speed sensor for lack of activity. The rationality will not run if a limp-in exists for MAP, throttle position, and engine coolant temperature. If vehicle speed sensor is below a minimum threshold for a period of time after the vehicle is operated at a sufficient load, a failure will be indicated.
The objective of the Idle "Speed Rationality" is to monitor the ability to achieve and maintain a steady idle condition. The Engine Speed Error is calculated by comparing the difference between the Idle Set Speed from the Engine Speed and filtering the result. If engine speed does not come within a calibrated threshold of target idle speed, a timer is started. If the timer reaches its maximum threshold without the idle set speed returning inside of its calibrated threshold, a soft failure is generated.
The objective of the Idle "Speed Rationality" is to monitor the ability to achieve and maintain a steady idle condition. The Engine Speed Error is calculated by comparing the difference between the Idle Set Speed from the Engine Speed and filtering the result. If engine speed does not come within a calibrated threshold of target idle speed, a timer is started. If the timer reaches its maximum threshold without the idle set speed returning inside of its calibrated threshold, a soft failure is generated.
Spark adjustment during a cold start is intended to provide quick response to idle speed variations. The Powertrain Control Module (PCM) monitors spark advance on a cold start over a period of time, then compares the average spark advance to a threshold.
The objective of the Dynamic Crankshaft Fuel Control (DCFC) is to reduce the fuel as much as possible during a cold start. The DCFC begins subtracting fuel from a high limit upon a cold start and keeps removing fuel in an attempt to get to a calibrated lean limit. DCFC stops removing fuel when rough idle is detected or the lean limit is reached.
The Speed Control Switch is hardwired to the Steering Column Control Module (SCCM). The SCCM is located near the top of the steering column below the steering wheel. The SCCM includes the steering column shroud, the Steering Angle Sensor (SAS), the Clockspring, the Multi-function Switch, a Steering Column Power Tilt and Telescope Switch (if equipped), and a trim cover. The speed control messages are bussed to the Powertrain Control Module (PCM) via the Can Bus.
The Speed Control Switch is hardwired to the Steering Column Control Module (SCCM). The SCCM is located near the top of the steering column below the steering wheel. The SCCM includes the steering column shroud, the Steering Angle Sensor (SAS), the Clockspring, the Multi-function Switch, a Steering Column Power Tilt and Telescope Switch (if equipped), and a trim cover. The speed control messages are bussed to the Powertrain Control Module (PCM) via the Can Bus.
The Speed Control Switch is hardwired to the Steering Column Control Module (SCCM). The SCCM is located near the top of the steering column below the steering wheel. The SCCM includes the steering column shroud, the Steering Angle Sensor (SAS), the Clockspring, the Multi-function Switch, a Steering Column Power Tilt and Telescope Switch (if equipped), and a trim cover. The speed control messages are bussed to the Powertrain Control Module (PCM) via the Can Bus.
The Speed Control Switch is hardwired to the Steering Column Control Module (SCCM). The SCCM is located near the top of the steering column below the steering wheel. The SCCM includes the steering column shroud, the Steering Angle Sensor (SAS), the Clockspring, the Multi-function Switch, a Steering Column Power Tilt and Telescope Switch (if equipped), and a trim cover. The speed control messages are bussed to the Powertrain Control Module (PCM) via the Can Bus.
The Speed Control Switch is hardwired to the Steering Column Control Module (SCCM). The SCCM is located near the top of the steering column below the steering wheel. The SCCM includes the steering column shroud, the Steering Angle Sensor (SAS), the Clockspring, the Multi-function Switch, a Steering Column Power Tilt and Telescope Switch (if equipped), and a trim cover. The speed control messages are bussed to the Powertrain Control Module (PCM) via the Can Bus.
The Speed Control Switch is hardwired to the Steering Column Control Module (SCCM). The SCCM is located near the top of the steering column below the steering wheel. The SCCM includes the steering column shroud, the Steering Angle Sensor (SAS), the Clockspring, the Multi-function Switch, a Steering Column Power Tilt and Telescope Switch (if equipped), and a trim cover. The speed control messages are bussed to the Powertrain Control Module (PCM) via the Can Bus.
The Speed Control Switch is hardwired to the Steering Column Control Module (SCCM). The SCCM is located near the top of the steering column below the steering wheel. The SCCM includes the steering column shroud, the Steering Angle Sensor (SAS), the Clockspring, the Multi-function Switch, a Steering Column Power Tilt and Telescope Switch (if equipped), and a trim cover. The speed control messages are bussed to the Powertrain Control Module (PCM) via the Can Bus.
The Powertrain Control Module (PCM) stores in its EEPROM vehicle information data transmitted over the CAN Bus from the BCM. If the stored information in the PCM does not match the information obtained over the CAN Bus, the DTC will set.
For specific relay location and type. Refer to FUSE LOCATIONS AND TYPES, SPECIFICATIONS .
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 Engine Oil Temperature (EOT) Sensor is a variable resistor that measures the temperature of the engine oil. It operates as a typical two wire sensor. The Powertrain Control Module (PCM) supplies the sensor with a 5-Volt reference and a sensor ground circuit. When the oil temperature is low, the sensor resistance is high. When the oil temperature is high, the sensor resistance is low.
The objective of the Dynamic Crankshaft Fuel Control (DCFC) is to reduce the fuel as much as possible during a cold start. The DCFC begins subtracting fuel from a high limit upon a cold start and keeps removing fuel in an attempt to get to a calibrated lean limit. DCFC stops removing fuel when rough idle is detected or the lean limit is reached.
The Speed Control Switch is hardwired to the Steering Column Control Module (SCCM). The SCCM is located near the top of the steering column below the steering wheel. The SCCM includes the steering column shroud, the Steering Angle Sensor (SAS), the Clockspring, the Multi-function Switch, a Steering Column Power Tilt and Telescope Switch (if equipped), and a trim cover. The speed control messages are bussed to the Powertrain Control Module (PCM) via the Can Bus.
The Powertrain Control Module (PCM) compares actual shutdown time to a calculated shutdown time value. The calculated shut down time value is based on the amount the Engine Coolant Temperature (ECT) should drop after a completely warmed up engine is shut down for a minimum of 8 hours. If the difference between actual shutdown time and the calculated shut down time is greater than a maximum value, a one trip failure will set. The shutdown time is measured again after 1 hour of ignition off time following the next engine warm up cycle. The PCM compares the shutdown time to a calculated value. If the difference is greater than a maximum value, the MIL is illuminated and a DTC will set.