ENGINE MANAGEMENT SYSTEM – TD6 DESCRIPTION AND OPERATION The APP sensor has two potentiometer tracks which each receive a V input voltage from the ECM. Track 1 provides an output of V with the pedal at rest and Vat full throttle. Track 2 provides an output of V with the pedal at rest and Vat full throttle. The signals from the two tracks are used by the ECM to determine fuelling for engine operation and also by the ECM and the EAT ECU to initiate a kickdown request for the automatic transmission. The ECM monitors the outputs from each of the potentiometer tracks and can determine the position, rate of change and direction of movement of the throttle pedal. The 'closed throttle' position signal is used by the ECM to initiate idle speed control and also overrun fuel cut-off.