P0122 APPS Sensor Signal Voltage Too Low

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DTC P0122: APP SENSOR SIGNAL VOLTAGE TOO LOW

Monitor & Set Conditions

Accelerator Pedal Position Sensor (APPS) voltage is monitored when engine is running. DTC may be stored if low voltage is detected on APPS signal circuit or low voltage is detected between Engine Control Module (ECM) and Powertrain Control Module (PCM).

Possible Causes

  • 5-volt Supply At APPS Shorted To ECM Sensor Ground
  • APPS Signal Circuit Shorted To ECM Sensor Ground
  • 5-volt Supply To Ground
  • APPS Signal Circuit Shorted To Ground
  • APPS Signal Circuit Open To ECM
  • PCM (APPS) Short To ECM Sensor Ground
  • ECM (APPS) To PCM (APPS) Circuit Shorted
  • ECM (APPS) To PCM (APPS) Circuit Open
  • Short To ECM Sensor Ground
  • Accelerator Pedal Position Sensor (APPS)
  • Engine Control Module
  • Powertrain Control Module

Testing

1. Turn ignition on with engine off. Using DRBIII(R) scan tool, check for ECM and PCM DTCs. Determine if DTC is set by ECM or PCM. If DTC is set by ECM, go to next step. If DTC is not set by ECM, go to step 7 .

2. Turn ignition off. Disconnect APPS sensor harness connector. APPS is located on bracket, just above fuel injection pump. Turn ignition on with engine off. Using DVOM, measure voltage between cylinder block (ground) and terminal No. 5 (Dark Blue/White wire) on APPS harness connector. If voltage is greater than 4.5 volts, go to next step. If voltage is 4.5 volts or less, go to step 6 .

3. Turn ignition off. Ensure APPS harness connector is still disconnected. Check for continuity between terminal No. 4 (Black/Yellow wire) and terminal No. 5 (Dark Blue/White wire) on APPS harness connector. If continuity does not exist, go to next step. If continuity exists, repair short between Dark Blue/White and Black/Yellow wires. The Black/Yellow wire is the sensor ground circuit.

4. Ensure APPS harness connector is still disconnected. Disconnect ECM harness connector. ECM is located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for continuity between terminal No. 4 (Black/Yellow wire) and terminal No. 3 (Light Blue/Black wire) on APPS harness connector. If continuity does not exist, go to next step. If continuity exists, repair short between Black/Yellow and Light Blue/Black wires.

5. Ensure APPS and ECM connectors are still disconnected. Check for continuity between ground and terminal No. 5 (Dark Blue/White wire) on APPS harness connector. If continuity does not exist, go to next step. If continuity exists, repair short to ground in Dark Blue/White wire.

6. Turn ignition off. Ensure APPS connector is still disconnected. Disconnect ECM harness connector. ECM is located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector. Check Dark Blue/White wire for continuity between terminal No. 5 on APPS harness connector and terminal No. 31 on ECM harness connector. If continuity does not exist, repair open in Dark Blue/White wire. If continuity exists, replace and program the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.

7. Turn ignition off. Disconnect PCM harness connectors. PCM is located at passenger's side rear corner of engine compartment. Check for continuity between ground and terminal A23 (Orange/Dark Blue wire) on PCM harness connector (APPS circuit). If continuity does not exist, go to step 9 . If continuity exists, go to next step.

8. Disconnect ECM harness connector. ECM is located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for continuity between ground and terminal A23 (Orange/Dark Blue wire) on PCM harness connector (APPS circuit). If continuity does not exist, test is complete. If continuity exists, repair short to ground in Orange/Dark Blue wire. 9. Ensure PCM harness connectors are still disconnected. Disconnect ECM connector. ECM is located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for circuit). If continuity does not exist, go to next step. If continuity exists, repair short to ground in Orange/Dark Blue wire.

10. Check Orange/Dark Blue wire for continuity between terminal No. 5 on APPS harness connector and terminal No. 31 on ECM harness connector. If continuity does not exist, repair open in Orange/Dark Blue wire. If continuity exists, go to next step.

11. Reconnect ECM harness connector. Ensure PCM harness connectors are still disconnected. Turn ignition on with engine off. Using DVOM, measure voltage between ground and terminal A23 (Orange/Dark Blue wire) on PCM harness connector (APPS circuit). If voltage is greater than 0.4 volt, test is complete. If voltage is 0.4 volt or less, go to next step.

12. Turn ignition off. Disconnect APPS harness connector. Check for continuity between ground and terminal A23 (Orange/Dark Blue wire) on PCM harness connector (APPS circuit). If continuity does not exist, replace APPS. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. If continuity exists, replace and program the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.