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Home › Chrysler › 2008 › Town & Country Limited › Repair and Diagnosis › Engine Performance › System › DTCS P0513 To P061C › P0579-Speed Control Switch 1 Performance › Diagnostic Test

Diagnostic Test

  1. DTC IS ACTIVE 

    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 can result in personal injury or death.
    NOTE: It may be necessary to test drive the vehicle and operate the speed control in order for this DTC to set.

    With a scan tool, select View DTCs.

    Is the status Active for this DTC? 

    Yes 

    1. Go to  3.

    No 

    1. Go to  2.
  2. DTC IS ACTIVE 

    Turn the ignition off.

    NOTE: Refer to the following table when diagnosing speed control switch voltage DTCs.
    - Switch 1 Voltage  Switch 2 Voltage 
    On/Off 0.89 3.74
    Cancel 1.79 3.05
    Set/Decel 3.37 1.37
    Accel/Res 4.04 2.25
    Diagnostic 4.54 4.54
    Distance 2.75 0.89

    Turn the ignition on.

    With the scan tool, monitor the Speed Control Signal 1 voltage.

    Move the Speed Control Switch to each position and note the voltage. Compare the voltage to the voltage listed in the table for each switch position.

    Is the voltage equal to the value listed in the table (+/- 5%) for each speed control switch position? 

    Yes 

    1. Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.

    No 

    1. Go to  3.
  3. SPEED CONTROL SIGNAL 1 VOLTAGE 
    Fig 1: Connecting Jumper Wire Between S/C Signal 1 Circuit And S/C Switch Ground Circuit In Control Switch Harness Connector
    GC0054096Courtesy of CHRYSLER LLC
    WARNING: Disconnect and isolate the battery negative (ground) cable before beginning steering wheel removal or installation. Allow the front airbag system capacitor to discharge for two minutes before removing the steering wheel or any front airbag system component. This will disable the front airbag system. Failure to disconnect the battery could result in accidental front airbag module deployment and possible personal injury.
    Do not place a non-deployed airbag face down on a hard surface as the airbag will propel into the air if accidentally deployed, and could result in serious or fatal injury.

    Turn the ignition off.

    Remove the Speed Control Switch in accordance with the Service Information.

    Turn the ignition on.

    With a scan tool, read the (V37) S/C Signal 1 voltage.

    NOTE: The Speed Control Signal 1 voltage should be above 4.8 volts with the Speed Control Switch connector disconnected.

    Connect a jumper wire between the (V37) S/C Signal 1 circuit and the (V937) S/C Switch Ground circuit in the Speed Control Switch harness connector.

    With a scan tool, read the (V37) S/C Signal 1 voltage.

    NOTE: The (V37) S/C Signal 1 voltage should be below.2 volts with the jumper wire in place.

    Is the Speed Control Signal 1 voltage above 4.8 volts with the Speed Control Switch connector disconnected and below.2 volts with the jumper wire in place? 

    Yes 

    1. Go to  9.

    No 

    1. Go to  4.
  4. (V37) S/C SIGNAL 1 CIRCUIT SHORTED TO VOLTAGE 
    Fig 2: Measuring Voltage Of (V37) S/C Signal 1 Circuit In Speed Control Switch Harness Connector
    GC0074267Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the Powertrain Control Module (PCM) connector.

    Turn the ignition on.

    Measure the voltage of the (V37) S/C Signal 1 circuit in the Speed Control Switch harness connector.

    Is there any voltage present? 

    Yes 

    1. Repair the (V37) S/C Signal 1 circuit for a short to voltage.
    2. Perform PCM VERIFICATION TEST .

    No 

    1. Go to  5.
  5. (V37) S/C SIGNAL 1 CIRCUIT SHORTED TO GROUND 
    Fig 3: Measuring Resistance Between Ground & (V37) S/C Signal 1 Circuit In Speed Control Switch Harness Connector
    GC0074268Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Measure the resistance between ground and the (V37) S/C Signal 1 circuit in the Speed Control Switch harness connector.

    Is the resistance above 100 ohms? 

    Yes 

    1. Go to  6.

    No 

    1. Repair the (V37) S/C Signal 1 circuit for a short to ground.
    2. Perform PCM VERIFICATION TEST .
  6. (V37) S/C SIGNAL 1 CIRCUIT SHORTED TO THE (V937) S/C SWITCH GROUND CIRCUIT 
    Fig 4: Measuring Resistance Between (V37) S/C Signal 1 Circuit & (V937) S/C Switch Ground Circuit In Speed Control Switch Harness Connector
    GC0074269Courtesy of CHRYSLER LLC

    Measure the resistance between the (V37) S/C Signal 1 circuit and the (V937) S/C Switch Ground circuit in the Speed Control Switch harness connector.

    Is the resistance above 100 ohms? 

    Yes 

    1. Go to  7.

    No 

    1. Repair the (V37) S/C Signal 1 circuit for a short to the (V937) S/C Switch Ground circuit.
    2. Perform PCM VERIFICATION TEST .
  7. (V37) S/C SIGNAL 1 CIRCUIT OPEN OR HIGH RESISTANCE 
    Fig 5: Checking S/C Signal 1 Circuit For Open Or High Resistance
    GC0059417Courtesy of CHRYSLER LLC
    NOTE: 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 (V37) S/C Signal 1 circuit between the Speed Control Switch harness connector and the appropriate terminal of special tool #8815.

    Is the resistance below 5.0 ohms? 

    Yes 

    1. Go to  8.

    No 

    1. Repair the (V37) S/C Signal 1 circuit for an open circuit or high resistance.
    2. Perform PCM VERIFICATION TEST .
  8. (V937) S/C SWITCH GROUND CIRCUIT OPEN OR HIGH RESISTANCE 
    Fig 6: Checking S/C Switch Ground Circuit For Open Or High Resistance
    GC0059418Courtesy of CHRYSLER LLC
    NOTE: 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 (V937) S/C Switch Ground circuit between the Speed Control Switch harness connector and the appropriate terminal of special tool #8815.

    Is the resistance below 5.0 ohms? 

    Yes 

    1. Go to  10.

    No 

    1. Repair the (V937) S/C Switch Ground circuit for an open circuit or high resistance.
    2. Perform PCM VERIFICATION TEST .
  9. SPEED CONTROL SWITCH 

    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 related connectors.

    Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.

    Look for the data to change or for the DTC to reset during the wiggle test.

    Refer to any Technical Service Bulletins that may apply.

    Were any problems found? 

    Yes 

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

    No 

    1. Replace the Speed Control Switch in accordance with the Service Information.
    2. Perform PCM VERIFICATION TEST .
  10. 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 related connectors.

    Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.

    Look for the data to change or for the DTC to reset during the wiggle test.

    Refer to any Technical Service Bulletins that may apply.

    Were any problems found? 

    Yes 

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

    No 

    1. Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information.
    2. Perform PCM VERIFICATION TEST .
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