Accelerator Pedal Position Sensor: Description and Operation

ACCELERATOR PEDAL POSITION SENSORS (APPS)

The ETC strategy uses pedal position sensors as an input to determine the driver demand.
1. There are three pedal position sensors required for system monitoring. APP1 has a negative slope (increasing angle, decreasing voltage) and APP2 & APP3 both have a positive slope (increasing angle, increasing voltage). During normal operation APP1 is used as the indication of pedal position by the strategy.
2. There are two VREF wires, two signal return wires and three signal wires (total of seven wires and pins) between the PCM and APPS assembly.
- 2-5 V Reference Voltage
- 2- Signal Return (ground)
- APP1 voltage with negative voltage slope (5-0)
- APP2 voltage with positive voltage slope (0-5)
- APP3 voltage with positive voltage slope (0-5)

3. The pedal position signal is converted to pedal travel degrees (rotary angle) by the PCM. The software then converts these degrees to counts, which is the input to the torque based strategy.

Electronic Throttle Body And Accelerator Pedal Assembly:

4. The three pedal position signals ensure a correct input to the PCM, if any one signal has a fault. The PCM knows if a signal is wrong by calculating where it should be, inferred by the other signals. A value will be substituted for a faulty signal if two out of the three signals are bad.