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Home › Jeep › 2007 › Wrangler X, Automatic › Repair and Diagnosis › Engine Performance › System › DTCS P1607 To P2138 › P2123-Accelerator Pedal Position Sensor 1 Circuit High › Diagnostic Test

Diagnostic Test

NOTE: When this DTC is Active the engine speed, torque, and vehicle speed are limited to a Limp in mode.

Start the engine and allow it to reach normal operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.
NOTE: Diagnose and repair any system voltage or sensor supply voltage DTCs before continuing with this test.
NOTE: If you are viewing data recorder information or Freeze Frame data the APP Sensor No. 2 is pulled low by the PCM as part of its system testing. This test happens every 320 milliseconds and may not show up on the scan tool but may show up on a data recorder or lab scope. It is acceptable to see the voltage close to zero with a normal sensor when using a data recorder/lab scope.

With the scan tool, select View DTCs.

Is the DTC Active at this time? 

Yes 

  1. Go to  2).

No 

  1. Go to  8).
  1. 2) (K23) APP SIGNAL 1 CIRCUIT SHORTED TO VOLTAGE 
    Fig 1: Measuring Voltage On APP Signal 1 Circuit
    GC0050985Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the PCM harness connectors.

    Disconnect the APP Sensor harness connector.

    Ignition on, engine not running.

    Measure the voltage on the (K23) APP Signal 1 circuit in the APP Sensor harness connector.

    Is there any voltage present? 

    Yes 

    1. Repair the short to voltage in the (K23) APP Signal 1 circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  3).
  2. 3) (K23) APP SIGNAL 1 CIRCUIT SHORTED TO THE (F855) 5-VOLT SUPPLY CIRCUIT 
    Fig 2: Measuring Resistance Between APP Signal 1 Circuit
    GC0050986Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Measure the resistance between the (K23) APP Signal 1 circuit and the (F855) 5-volt Supply circuit in the APP Sensor harness connector.

    Is the resistance below 100 ohms? 

    Yes 

    1. Repair the short between the (K23) APP Signal 1 circuit and the (F855) 5-volt Supply circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  4).
  3. 4) (K23) APP SIGNAL 1 CIRCUIT SHORTED TO THE (F856) 5-VOLT SUPPLY CIRCUIT 
    Fig 3: Measuring Resistance Between APP Signal 1 Circuit And 5-Volt Supply Circuit
    GC0050987Courtesy of CHRYSLER LLC

    Measure the resistance between the (K23) APP Signal 1 circuit and the (F856) 5-volt Supply circuit in the APP Sensor harness connector.

    Is the resistance below 100 ohms? 

    Yes 

    1. Repair the short between the (K23) APP Signal 1 circuit and the (F856) 5-volt Supply circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  5).
  4. 5) (K167) APP RETURN 1 CIRCUIT OPEN 
    Fig 4: Measuring Resistance Of APP Return 1 Circuit
    GC0050988Courtesy of CHRYSLER LLC
    CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

    Measure the resistance of the (K167) APP Return 1 circuit from the APP Sensor harness connector to the appropriate terminal of special tool #8815.

    Is the resistance below 5.0 ohms? 

    Yes 

    1. Go to  6).

    No 

    1. Repair the open in the (K167) APP Return 1 circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .
  5. 6) ACCELERATOR PEDAL POSITION SENSOR 

    Connect the PCM harness connectors.

    Ignition on, engine not running.

    With a scan tool, monitor the APP Sensor 1 voltage.

    Is the voltage above 0 volts? 

    Yes 

    1. Go to  7).

    No 

    1. Verify that there is good pin to terminal contact in the APPS and the Powertrain Control Module connectors. If OK, replace the APP Sensor Assembly per Service Information. After installation is complete, use a scan tool and select the ETC RELEARN function to relearn the APPS values.
    2. Perform POWERTRAIN VERIFICATION TEST .
  6. 7) POWERTRAIN CONTROL MODULE (PCM) 

    Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Accelerator Pedal Position Sensor and the Powertrain Control Module (PCM).

    Look for any chafed, pierced, pinched, or partially broken wires.

    Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the APPS and the Powertrain Control Module connectors.

    Refer to any Technical Service Bulletins that may apply.

    Were there any problems found? 

    Yes 

    1. Repair as necessary.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Replace and program the Powertrain Control Module per Service Information.
    2. Perform POWERTRAIN VERIFICATION TEST .
  7. 8) APP SENSOR NO. 1 SWEEP 

    Ignition on, engine not running.

    With a scan tool, monitor the Accelerator Pedal Position Sensor voltage.

    Slowly press the Accelerator Pedal down.

    Does voltage start at approximately 0.45 of a volt and go above 4.6 volts with a smooth transition? 

    Yes 

    1. Refer to INTERMITTENT CONDITION .

    No 

    1. Verify that there is good pin to terminal contact in the APPS and the Powertrain Control Module connectors. If OK, replace the APP Sensor Assembly per Service Information. After installation is complete, use a scan tool and select the ETC RELEARN function to relearn the APPS values.
    2. Perform POWERTRAIN VERIFICATION TEST .
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