Accelerator Pedal Position (APP) Sensors

The ETC strategy uses pedal position as an input to determine the driver demand.

1. There are 3 pedal position sensors required for system monitoring. The APP1 has a negative slope (increasing angle, decreasing voltage) and APP2 and APP3 both have a positive slope (increasing angle, increasing voltage). During normal operation APP1 is used as the indication by the strategy.
2. There are 2 VREF signals (ETCEREF1 and ETCREF2), 2 signal returns (ETCRTN1 and ETCRTN2), and 3 signals (APPS1, APPS2, and APPS3) between the PCM and APP assembly.
   • 5 volt reference voltage circuits (2)
   • Signal return (ground) circuits (2)
   • APP1 voltage with negative voltage slope 5 volts to 0 volts
   • APP2 voltage with positive voltage slope 0 volts to 5 volts
   • APP3 voltage with positive voltage slope 0 volts to 5 volts
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.
4. The 3 pedal position signals provide a correct input to the PCM should any one signal have a fault. The PCM knows if a signal is wrong by calculating where it should be, inferred from the other signals. A value is substituted for a faulty signal if 2 out of the 3 signals are bad.
   Fig 1: Identifying Electronic Throttle Body (ETB) And Accelerator Pedal Assembly

   Courtesy of FORD MOTOR CO.