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Home >> Jeep >> 2012 >> Liberty Limited Jet, 4WD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> 3.7L - DTCS P0206 To P0579 >> Diagnosis And Testing >> P0579-Speed Control Switch 1 Performance >> Diagnostic Test

Diagnostic Test

  1. ACTIVE DIAGNOSTIC TROUBLE CODE (DTC) 
    1. Start the engine and allow it to idle for at least 60 seconds.
      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 may result in possible serious or fatal injury.

      NOTE:

      It may be necessary to test drive the vehicle and operate the speed control in order for this DTC to set.

    2. With a scan tool, select View DTCs.

      Is the DTC Active at this time?

      Yes 

      • Go To  2.

      No 

  2. SPEED CONTROL SWITCH 
    1. Turn the ignition off.
    2. Remove and disconnect the Speed Control Switch from the steering wheel in accordance with the service information.
    3. Measure the resistance across each Speed Control Switch.
    4. Monitor the Ohmmeter while pressing each function button on the switch.
    5. The following resistance specs are taken between terminals (V71) S/C Signal 1 and (V937) S/C Return circuits of the Switch when holding the switch button in the following position:
      • Not pressing any switch - 20.5 kOhms
      • On/Off - 0.47 kOhms
      • Set - 5.49 kOhms
      • Coast - 2.94 kOhms
      • Cancel - 1.24 kOhms
      • Resume/Accel - 15.4 kOhms

      Does the function on the Speed Control Switches have the correct resistance value?

      Yes 

      • Go To  3.

      No 

  3. (V71) S/C SIGNAL 1 CIRCUIT SHORTED TO VOLTAGE 
    Fig 1: Measuring Voltage On S/C Signal Circuit At Speed Control Harness Connector
    GC0099557Courtesy of CHRYSLER GROUP, LLC
    1. Disconnect the C3 PCM harness connector.
    2. Ignition on, engine not running.
    3. Measure the voltage on the (V71) S/C Signal 1 circuit in the S/C Switch harness connector.

      Is there any voltage present?

      Yes 

      No 

      • Go To  4.
  4. (V71) S/C SIGNAL 1 CIRCUIT OPEN 
    Fig 2: Measuring Resistance Of S/C Signal 1 Circuit
    GC0102031Courtesy of CHRYSLER GROUP, 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 the PCM Pinout Box (special tool #8815A, Kit, NGC, 38 Position) to perform diagnosis.

    1. Turn the ignition off.
    2. Measure the resistance of the (V71) S/C Signal 1 circuit from the Speed Control Switch to the appropriate terminal of PCM Pinout Box (special tool #8815A, Kit, NGC, 38 Position).

      Is the resistance below 5.0 Ohms for each measurement?

      Yes 

      • Go To  5.

      No 

  5. (V937) S/C RETURN CIRCUIT OPEN 
    Fig 3: Measuring Resistance Of S/C Switch Ground Circuit
    GC0102032Courtesy of CHRYSLER GROUP, 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 the PCM Pinout Box (special tool #8815A, Kit, NGC, 38 Position) to perform diagnosis.

    1. Measure the resistance of the (V937) S/C Return circuit from the S/C Switch harness connector to the appropriate terminal of PCM Pinout Box (special tool #8815A, Kit, NGC, 38 Position).

      Is the resistance below 5.0 Ohms?

      Yes 

      • Go To  6.

      No 

  6. (V71) S/C SIGNAL 1 CIRCUIT SHORTED TO GROUND 
    Fig 4: Measuring Resistance Between Ground And S/C Switch Signal Circuit
    GC0099562Courtesy of CHRYSLER GROUP, LLC
    1. Measure the resistance between ground and the (V71) S/C Signal 1 circuit in the S/C Switch harness connector.

      Is the resistance below 100 Ohms?

      Yes 

      No 

      • Go To  7.
  7. (V71) S/C SIGNAL 1 CIRCUIT SHORTED TO THE (V937) S/C RETURN CIRCUIT 
    Fig 5: Measuring Resistance Between S/C Signal 1 Circuit & S/C Return Circuit In S/C Switch Harness Connector
    GC0102033Courtesy of CHRYSLER GROUP, LLC
    1. Measure the resistance between the (V71) S/C Signal 1 circuit and the (V937) S/C Return circuit in the S/C Switch harness connector.

      Is the resistance below 5.0 Ohms?

      Yes 

      • Repair the short between the (V71) S/C Signal 1 circuit and the (V937) S/C Return circuit.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to 3.7L - POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  8.
  8. SPEED CONTROL SWITCH VOLTAGE VALUES 
    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/DECEL 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
    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 the PCM Pinout Box (special tool #8815A, Kit, NGC, 38 Position) and PCM Pinout Box Adapter (special tool #8815-1, PCM Pinout Box Adapter) to perform diagnosis.

    1. Install the PCM Pinout Box (special tool #8815-1, PCM Pinout Box Adapter) on the C3 PCM harness connector.
    2. Connect the S/C Switch harness connectors.
    3. Connect the Clockspring harness connectors.
    4. Turn the ignition on.
    5. With a scan tool, monitor the S/C Switch voltage readings.
    6. 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 PCM Pinout Box (special tool #8815A, Kit, NGC, 38 Position).
    7. Monitor the Voltmeter.
    8. With a scan tool, monitor the S/C Switch voltage readings.
    9. 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 value?

      Yes 

      • Verify that there is good pin to terminal contact in the Switches and Powertrain Control Module connectors. If OK, replace the Speed Control Switch.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to 3.7L - POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  9.
  9. POWERTRAIN CONTROL MODULE (PCM) 
    1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Speed Control Switch and the Powertrain Control Module (PCM).
    2. Look for any chafed, pierced, pinched, or partially broken wires.
    3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Switch and Control Module connectors.
    4. Perform any Technical Service Bulletins that may apply.

      Were there any problems found?

      Yes 

      No 

      • Replace and program the Powertrain Control Module in accordance with the service information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to 3.7L - POWERTRAIN VERIFICATION TEST .
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