DTC 21, App No. 1 Circuit High (Models With Pcm): Notes

Accelerator Pedal Position (APP) module provides a voltage signal that changes relative to accelerator position. There are 3 sensors located within APP module that are scaled differently. DTC 21 will set when voltage is greater than 4.75 volts for 2 seconds on APP No. 1 sensor. PCM will default to input from APP No. 1 sensor being ignored. A current and history DTC will set but will not turn on SERVICE THROTTLE SOON light. Throttle will operate normally as long as there is only one sensor malfunctioning.

If 2 different APP sensors have a malfunction, SERVICE THROTTLE SOON light will light and PCM will limit power. If 3 APP sensors malfunction, SERVICE THROTTLE SOON light will light and PCM will only allow engine to operate at idle.

1. This step determines if DTC 21 is result of a hard failure or an intermittent condition.
2. This step checks PCM and wiring.
3. This step checks for an open in ground circuit.