LR3/Disco 3
manifold in the engine compartment. The system comprises three main components:
Electronic throttle control valve
Accelerator pedal position sensor (APP)
ECM
When the accelerator pedal is depressed the APP sensor provides a change in the monitored signals. The ECM
compares this against an electronic “map” and moves the electronic throttle valve via a pulse width modulated (PWM)
control signal which is in proportion to the APP angle signal. The system is required to:
Regulate the calculated intake air load based on the accelerator pedal sensor input signals and programmed
mapping.
Monitor the drivers input request for cruise control operation.
Automatically position the electronic throttle for accurate cruise control.
Perform all dynamic stability control throttle control interventions.
Monitor and carry out maximum engine and road speed cut out.
A software strategy within the ECM enables the throttle position to be calibrated each ignition cycle. When the ignition is
turned ON, the ECM performs a self test and calibration routine on the electronic throttle by opening and closing the
throttle fully.
Electronic Throttle Pin Out Table
ACCELERATOR PEDAL POSITION SENSOR (APP)
The APP sensors are located on the accelerator pedal assembly.
The APP sensors are used to determine the driver's request for vehicle speed, acceleration and deceleration. This value
is used by the ECM and the throttle is opened to the correct angle by an electric motor integrated into the throttle body.
The APP Sensor signals are checked for range and plausibility. Two separate reference voltages are supplied to the
pedal. Should one sensor fail, the other is used as a 'limp – home' input. In limp home mode due to an APP signal failure
the ECM will limit the maximum engine speed to 2000 rpm.
Accelerator Pedal Position Sensor (APP) Pin Out Table
Pin No Description
1
Motor -
2
Motor +
3
Sensor ground
4
Sensor 2 signal
5
Sensor 1 signal
6
5 volt supply
Pin No Description
