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  • P0123 APPS Sensor Signal Voltage Too High

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    Mopar1973Man

    DTC P0123: APP SENSOR SIGNAL VOLTAGE TOO HIGH

    Monitor & Set Conditions

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

    Possible Causes

    • 5-volt Supply At APPS Shorted To Voltage (Engine Running)
    • APPS 5-volt Supply Circuit Shorted To Voltage
    • APPS Signal Circuit Shorted To Voltage (Engine Running)
    • APPS Signal Circuit Shorted To Voltage
    • APPS Return Circuit Open
    • APPS Signal Circuit Open From APPS To ECM
    • APPS 5-volt Supply Circuit Open
    • PCM (APPS) Circuit Shorted To Voltage With The Engine Running
    • PCM (APPS) Short To Voltage With Ignition Key On
    • APPS Open Between PCM And ECM
    • Open APPS Circuit
    • Accelerator Pedal Position Sensor (APPS)
    • Engine 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 11.

    2. Turn ignition off. Disconnect APPS sensor harness connector. APPS is located on a 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 the voltage is greater than 5.5 volts, go to next step. If the voltage is 5.5 volts or less, go to step 5.

    3. Turn ignition off. Check for poor connection/terminal contact at APPS harness connector. Repair as necessary. Ensure APPS harness connector is still disconnected. Turn ignition on with engine off. Using DVOM, measure voltage between terminal No. 5 (Dark Blue/White wire) and terminal No. 4 (Black/Yellow wire) on APPS harness connector. If the voltage is 5.5 volts or less, go to next step. If the voltage is greater than 5.5 volts, repair short to voltage in Dark Blue/White wire.

    4. Turn ignition off. Ensure APPS harness connector is still disconnected. Disconnect ECM harness connector. ECM is located on driver's side of the engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for poor connection/terminal contact at ECM harness connector. Repair as necessary. Turn ignition on with engine off. Using DVOM, measure voltage between cylinder block (ground) and terminal No. 5 (Dark Blue/White wire) on APPS connector. If the voltage is greater than 5.5 volts, repair short to voltage on Dark Blue/White wire between APPS and ECM. If the voltage is 5.5 volts or less, replace and program the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.

    5. Check for poor connection/terminal contact at APPS harness connector. Repair as necessary. Ensure APPS connector is still disconnected. Start engine. Using a DVOM, measure voltage between cylinder block (ground) and terminal No. 3 (Light Blue/Black wire) on APPS connector. If the voltage is greater than 5.5 volts, go to next step. If the voltage is 5.5 volts or less, go to step 8.

    6. Turn ignition off. Turn ignition on with engine off. Using DVOM, measure voltage between cylinder block (ground) and terminal No. 3 (Light Blue/Black wire) on APPS connector. If the voltage is greater than 5.5 volts, go to next step. If the voltage is 5.5 volts or less, repair short to voltage on Light Blue/Black wire between APPS and ECM (short only exists when the engine is running).

    7. Turn ignition off. Ensure APPS harness connector is still disconnected. Disconnect ECM harness connector. ECM is located on driver's side of the engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for poor connection/terminal contact at ECM harness connector. Repair as necessary. Turn ignition on with engine off. Using DVOM, measure voltage between cylinder block (ground) and terminal No. 3 (Light Blue/Black wire) on APPS connector. If the voltage is greater than 5.5 volts, repair short to voltage on Light Blue/Black wire between APPS and ECM (short only exists when the ignition is on). If the voltage is 5.5 volts or less, replace and program the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.

    8. Turn ignition off. Ensure APPS harness connector is still disconnected. Disconnect ECM harness connector. ECM is located on driver's side of the engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for poor connection/terminal contact at ECM harness connector. Repair as necessary. Check Black/Yellow wire for continuity between terminal No. 4 on APPS harness connector and terminal No. 32 on ECM harness connector. If continuity exists, go to next step. If continuity does not exist, repair open in Black/Yellow wire between APPS and ECM.

    9. Ensure APPS harness connector and ECM harness connector are still disconnected. Check Light Blue/Black wire for continuity between terminal No. 3 on APPS harness connector and terminal No. 25 on ECM harness connector. If continuity exists, go to next step. If continuity does not exist, repair open in Light Blue/Black wire between APPS and ECM.

    10. Ensure APPS harness connector and ECM harness connector are still disconnected. 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 exists, go to next step. If continuity does not exist, replace APPS. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.

    11. Turn ignition off. Disconnect PCM harness connectors. PCM is located at passenger's side rear corner of engine compartment. Check for poor connection/terminal contact at PCM harness connectors. Repair as necessary. Start engine and allow the engine to idle. Using DVOM, measure voltage between cylinder block (ground) and terminal No. 23 (Orange/Dark Blue wire) on PCM harness connector C1. If the voltage is greater than 5.5 volts, go to next step. If the voltage is 5.5 volts or less, go to step 14.

    12. Turn ignition off. Ensure PCM harness connectors are still disconnected. Turn ignition on with engine off. Using DVOM, measure voltage between cylinder block (ground) and terminal No. 23 (Orange/Dark Blue wire) on PCM harness connector C1. If the voltage is greater than 5.5 volts, go to next step. If the voltage is 5.5 volts or less, repair short to voltage on Orange/Dark Blue wire between PCM and ECM (short only exists when the engine is running).

    13. Turn ignition off. Ensure PCM harness connectors are still disconnected. Disconnect ECM harness connector. ECM is located on driver's side of the engine, just in front of fuel transfer pump and contains a 50- pin connector. Check for poor connection/terminal contact at ECM harness connector. Repair as necessary. Turn ignition on with engine off. Using DVOM, measure voltage between cylinder block (ground) and terminal No. 23 (Orange/Dark Blue wire) on PCM harness connector C1. If the voltage is greater than 5.5 volts, repair short to voltage on Orange/Dark Blue wire between PCM and ECM (short only exists when the ignition is on). If the voltage is 5.5 volts or less, replace and program the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.

    14. Turn ignition off. Ensure PCM harness connectors are still disconnected. Disconnect ECM harness connector. ECM is located on driver's side of the engine, just in front of fuel transfer pump and contains a 50- pin connector. Check for poor connection/terminal contact at PCM harness connectors. Repair as necessary. Check continuity of Orange/Dark Blue wire between terminal No. 23 on PCM harness connector C1 and terminal No. 28 on ECM harness connector. If continuity does not exist, repair open in Orange/Dark Blue wire between PCM and ECM. If continuity exists, the test is complete. Clear DTCs from both ECM and PCM.

     

     

    If you find that your APPS is bad you can replace it with a Timbo Apps from the Mopar1973man Store.

     

     

     



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