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Home >> GMC >> 1994 >> Forward Control 4.3 Z, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 6.5L Diesel >> Diagnostic Trouble Code Charts >> DTC 22 - App No. 1 Circuit Low (Models With Pcm) >> Notes

DTC 22 - App No. 1 Circuit Low (Models With Pcm): Notes

The Accelerator Pedal Position (APP) module provides a voltage signal that changes relative to accelerator position. There are 3 sensors located within the APP module that are scaled differently. DTC 22 will set when voltage is less than .25 volt for 2 seconds on APP No. 1 sensor.

PCM will default to the input from the APP No. 1 sensor being ignored. A current and history DTC will set but will not turn on the SERVICE THROTTLE SOON light. The throttle will operate normally as long as there is only one sensor malfunctioning. If 2 different APP sensors have a malfunction, the SERVICE THROTTLE SOON light will light and the PCM will limit power. If 3 APP sensors malfunction, the SERVICE THROTTLE SOON light will light and the PCM will only allow the engine to operate at idle.

NOTE: Test numbers refer to numbers on diagnostic chart.
  1. This step determines if DTC 22 is the result of a hard failure or an intermittent condition.
  2. This step checks the PCM and wiring.
  3. This step checks for a faulty connection or sensor.
  4. This step checks the ground circuit.