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Home >> Jeep >> 2009 >> Wrangler X, Standard >> Repair and Diagnosis >> Engine Performance >> System >> DTCS P0579 To P0645 - NGC >> P0593-Speed Control Switch 2 Circuit High >> Diagnostic Test

Diagnostic Test

  1. ACTIVE 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 step  2

      No 

  2. SPEED CONTROL SWITCHES 
    1. Turn the ignition off.
    2. Remove and disconnect the Speed Control Switches from the steering wheel.
    3. Measure the resistance across each Speed Control Switch.
    4. Monitor the Ohmmeter while pressing each function button on each switch.
    5. The following resistance specs are taken between terminals (V72) S/C Switch No. 1 Signal and (V937) S/C Switch Ground circuit 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 step  3

      No 

  3. (V72) S/C SIGNAL 2 CIRCUIT SHORTED TO VOLTAGE 
    Fig 1: Checking S/C Signal 2 Circuit
    GC0102034Courtesy of CHRYSLER LLC
    1. Disconnect the C3 PCM harness connector.
    2. Ignition on, engine not running.
    3. Measure the voltage on the (V72) S/C Signal 2 circuit in the S/C Switch harness connector.

      Is there any voltage present?

      Yes 

      No 

      • Go to step  4
  4. (V72) S/C SIGNAL 2 CIRCUIT OPEN 
    Fig 2: Checking S/C Signal 2 Circuit
    GC0102035Courtesy 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 PCM Pinout Box 8815 to perform diagnosis.
    1. Turn the ignition off.
    2. Measure the resistance of the (V72) S/C Signal 2 circuit from the Speed Control Switch to the appropriate terminal of PCM Pinout Box 8815.

      Is the resistance below 5.0 Ohms for each measurement?

      Yes 

      • Go to step  5

      No 

  5. (V937) S/C SWITCH GROUND CIRCUIT OPEN 
    Fig 3: Checking S/C Switch Circuit
    GC0102032Courtesy of CHRYSLER LLC
    1. Measure the resistance of the (V937) S/C Switch Ground circuit from the S/C Switch harness connector to the appropriate terminals of PCM Pinout Box 8815.

      Is the resistance below 5.0 Ohms for each measurement?

      Yes 

      • Go to step  6

      No 

  6. 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 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 PCM Pinout Box 8815 and PCM Pinout Box Adapter 8815-1 to perform diagnosis.
    1. Using a voltmeter check the voltage on the (V38) S/C Signal 2 circuit at the appropriate terminal of the PCM Pinout Box 8815.
      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.
    2. Start the engine and allow it to reach normal operating temperature.
    3. Monitor the voltmeter.
    4. Allow the engine to idle.
    5. With a scan tool, monitor the S/C Switch voltage readings.
    6. 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 

      No 

      • Go to step  7
  7. 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 Powertrain Control Module connectors.
    4. Perform any Technical Service Bulletins that may apply.

      Were there any problems found?

      Yes 

      No 

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