Accelerator Pedal Position (APP) Sensor

Accelerator Pedal Position (APP) Sensor:

The Accelerator Pedal Position (APP) sensor is made up of 2 sensors that are housed inside one assembly. The APP sensor is located on a bracket above the accelerator pedal. The Engine Control Module (ECM) supplies a separate 5-volt reference and the ground circuit for each of the sensors. The 5-volt reference for APP sensor 1 is supplied from the same source in the ECM as the 5-volt reference for the mass air flow sensor and the fuel tank pressure sensor. The 5-volt reference for APP sensor 2 is supplied from the same source in the ECM as the 5-volt reference for the Throttle Position (TP) sensors. The 5-volt reference voltage for all of the sensors is supplied on separate ECM terminals, but the terminals are connected internally to the shared voltage supply. The APP sensor sends a signal from each of the sensors to the ECM indicating the acceleration demand of the driver. The ECM actuates the throttle plates based on this information. The APP sensor 1 signal voltage increases as the throttle opens, from about 0.4 volts at closed throttle to above 3.5 volts at Wide Open Throttle (WOT). The APP sensor 2 signal voltage also increases as the throttle opens, but at a slightly different rate. The APP sensor 2 signal voltage increases from about 0.2 volts at closed throttle to about 1.8 volts at wide open throttle. The APP sensor 1 is the main control of the system. The APP sensor 2 is used for comparison of the APP sensor 1. The ECM constantly monitors these two sensors and if the sensors are not within a calibrated value a Diagnostic Trouble Code (DTC) will set.