Pedal, Accelerator: Operation
- The Accelerator Pedal Position Sensor (APPS) is a variable resistor that provides the Powertrain Control Module (PCM) with an input signal (voltage). The signal represents throttle blade position. As the position of the accelerator pedal changes, the resistance of the APPS changes.
- The Electronic Throttle Control (ETC) system uses two (APPS) to monitor the accelerator pedal position. The APPS 1 and 2 are integrated into one assembly located at the pedal assembly. Each sensor has a 5 volt reference circuit, a low reference circuit, and a signal circuit. The Powertrain Control Module (PCM) reads the two signals individually and then compares the two signals as a redundant check of the pedal position. One of the sensors will fluctuate somewhere between 0 volts and 5.0 volts and the other sensor will fluctuate somewhere between 0 volts and 2.5 volts. The fluctuation of the two sensors should move proportionately. When operating properly, the voltage reading of the sensor operating on the 2.5 volt scale will always be approximately half of the voltage reading of the sensor on the 5.0 volt scale.