Pedal Request

Pedal Request





General
Two potentiometers are integrated in the accelerator pedal bracket. Potentiometer 1 provides ECM with information on the driver's torque request in the form of a voltage signal 0-5 V.

Potentiometer 2 is a safety potentiometer that provides ECM with information on the pedal position in the form of a voltage signal 0-2.5 V. This voltage is used to ensure that information from potentiometer 1 is reliable.

If the information from the potentiometers does not agree, one of them must be malfunctioning. The engine throttle control will then go into limp-home mode.

Function
Pedal potentiometer 1 provides ECM with information on the drivers torque request. The pedal position together with the engine speed gives a requested torque using a matrix. The torque request varies between 0 Nm (idling) and a value that is somewhat greater then the maximum torque allowed for the engine.

To obtain good driveability and response to the pedal position, a given pedal position will give a higher torque at lower engine speeds and lower torque at higher engine speeds.

The torque request finally results in a requested air mass per combustion so that the engine can attain the requested torque.

Adaptation of pedal position
When the pedal is completely released, potentiometer 1 adapts the voltage value for the released pedal. This constitutes the idling position of the pedal, the lowest voltage value for potentiometer 1 is defined as a completely released pedal. Adaption occurs each time the ignition is switched on.