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Home >> Jeep >> 2008 >> Liberty Limited, 4WD, Part Time >> Repair and Diagnosis >> Engine Performance >> System >> DTCS P0571 To P063A >> P0592-Speed Control Switch 2 Circuit Low >> Diagnostic Test
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Diagnostic Test

  1. ACTIVE DTC 

    Start the engine.

    Allow the engine 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.

    With a scan tool, select View DTCs.

    NOTE: It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data.

    Is the DTC Active at this time? 

    Yes 

    1. Go To  2.

    No 

    1. Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
  2. SPEED CONTROL SWITCH 

    With the scan tool, monitor the Speed Control Switch voltage.

    Disconnect the Speed Control Switch harness connector.

    Did the voltage change to above 4.7 volts? 

    Yes 

    1. Replace the Speed Control Switch.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go To  3.
  3. (V72) S/C SIGNAL 2 CIRCUIT SHORTED TO GROUND 
    Fig 1: Measuring Resistance Between Ground And S/C Switch Signal Circuits At S/C Switch Harness Connectors
    GC0062166Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the C3 PCM harness connector.

    Measure the resistance between ground and the (V72) S/C Signal 2 circuit in the Switch harness connector.

    Is the resistance below 100 ohms? 

    Yes 

    1. Repair the short to ground in the (V72) S/C Signal 2 circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go To  4.
  4. (V72) S/C SIGNAL 2 CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT 
    Fig 2: Measuring Resistance Between S/C Return Circuit And S/C Signal Circuits In S/C Switch Harness Connector
    GC0062164Courtesy of CHRYSLER LLC

    Measure the resistance between the (V72) S/C Signal 2 circuit and the (V937) S/C Return circuit in the Switch harness connector.

    Is the resistance below 5.0 ohms? 

    Yes 

    1. Repair the short between the (V72) S/C Signal 2 circuit and the (V937) S/C Return circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go To  5.
  5. (V72) S/C SIGNAL 2 CIRCUIT OPEN 
    Fig 3: Measuring Resistance Of (V72) S/C Signal 2 Circuit From Speed Control Switch To Appropriate Terminal Of Special Tool #8815
    GC0059419Courtesy 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 (V72) S/C Signal 2 circuit from the Switch 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 excessive resistance in the (V72) S/C Signal 2 circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .
  6. SPEED CONTROL SWITCH VOLTAGE VALUES 
    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 and #8815-1 to perform diagnosis.

    Install Miller Special Tool #8815-1 on the C3 PCM harness connector.

    Connect the S/C Switch harness connectors.

    Connect the SCCM harness connectors.

    Turn the ignition on.

    With a scan tool, monitor the S/C Switch voltage readings.

    Using a voltmeter check the voltage on the (V37) S/C Signal 1 circuit and the (V38) S/C Signal 2 circuit at the appropriate terminals of the special tool #8815.

    Monitor the voltmeter.

    With a scan tool, monitor the S/C Switch voltage readings.

    SWITCH POSITION  SWITCH No.1 VOLTAGE VALUE  SWITCH No.2 VOLTAGE VALUE 
    NO SWITCHES PRESSED 4.31 to 4.78 volts 4.31 to 4.78 volts
    ON/OFF PRESSED 0.59 to 1.13 volts 3.53 to 3.92 volts
    RES/ACCEL PRESSED 3.88 to 4.17 volts 2.04 to 2.47 volts
    SET PRESSED 3.16 to 3.56 volts 1.17 to 1.56 volts
    COAST PRESSED 2.57 to 2.94 volts 0.77 to 1.09 volts
    CANCEL PRESSED 1.59 to 1.99 volts 2.84 to 3.25 volts

    Compare the voltage readings on the voltmeter to what the scan tool displayed.

    Are the voltage readings out of the listed specification and is there less than a 0.2 of a volt difference between the voltmeter switch values and the scan tool switch values? 

    Yes 

    1. Verify that there is good pin to terminal contact in the Switches and Powertrain Control Module connectors. Replace the Speed Control Switch if no problems were found in the connectors.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go To  7.
  7. POWERTRAIN CONTROL MODULE (PCM) 

    Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Speed Control Switch 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 Switch and 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 .
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