Range Rover Sport (LS) V8-4.2L SC (2006)
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Accelerator Pedal Position Sensor: Description and Operation
Accelerator Pedal Position Sensor
The APP (accelerator pedal position) is integral to the accelerator pedal assembly.
The APP (accelerator pedal position) sensor enables the ECM (engine control module) to determine the throttle position requested by the driver on the
accelerator pedal.
The APP (accelerator pedal position) sensor is installed on the pedal box and consists of a twin track potentiometer with wipers driven by a linkage
connected to the accelerator pedal. Each potentiometer track has a 5 volts supply and ground connection from the ECM (engine control module), and
produces a linear signal voltage to the ECM (engine control module) proportional to the position of the accelerator pedal. The signal voltage from track
1 of the potentiometer is approximately double that of the signal voltage from track 2.
From the sensor signals, the ECM (engine control module) determines driver demand as a percentage of pedal travel, where 0% is with the pedal
released and 100% is with the pedal fully depressed. Driver demand is then used to calculate throttle angle, fuel quantity and ignition timing. The ECM
(engine control module) also outputs driver demand on the CAN (controller area network) system, for use by the brake and gearbox control systems.
The ECM (engine control module) stores the signal values that correspond with closed and wide open throttle, and adapts to new values to accommodate
component wear or replacement.
The signals from the APP (accelerator pedal position) sensor are monitored by the ECM (engine control module) for short and open circuits and
plausibility. If a fault is detected, the ECM (engine control module) :
^
Stores a related fault code in memory.
^
Illuminates the SERVICE ENGINE warning lamp in the instrument pack.
^
Inhibits the driver demand message on the CAN (controller area network) bus, which disables the Hill Descent Control (HDC) function of the
ABS (anti-lock brake system) modulator and reduces the performance of the automatic gearbox (harsh gear changes and loss of kickdown).
^
Adopts a throttle limp home mode.
The throttle limp home mode adopted depends on the nature of the fault:
^
If a fault is detected with one potentiometer track, the ECM (engine control module) limits vehicle acceleration by limiting throttle plate opening.
^
If a fault is detected with both potentiometer tracks, the ECM (engine control module) uses the throttle plate to run the engine at a fixed speed of
1472 rpm while the brake pedal is released, and idle speed (750 rpm) while the brake pedal is pressed or if there is a brake pedal sensor fault.
^
If there is a process fault in the ECM (engine control module), the ECM (engine control module) either uses fuel injection cut-off to limit engine
speed to 1300 rpm or disables fuel injection to stop the engine.
C0787 Accelerator Pedal Position Sensor Pin Out Table
