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Home >> Dodge and Ram >> 2019 >> ProMaster City Base >> Repair and Diagnosis >> Engine Performance >> System >> 2.4L - DTCS P0304 To P062A >> DTC Troubleshooting >> P0579-Speed Control Switch 1 Performance >> Diagnostic Test

Diagnostic Test

  1. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE DTC TO RETURN 
    1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
    2. For future reference, run and save a vehicle Scan Report and all related recorded data.
    3. With the scan tool, erase all DTCs.
    4. Turn the ignition off for a minimum of 10.0 seconds.
    5. Test drive the vehicle and operate the speed control system. Select all of the speed control functions during the test drive.
    6. Using the When Monitored and Set Conditions above and recorded data, operate the vehicle in the conditions that set the DTC.
    7. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Go to 2

      No 

  2. CHECK THE S/C (V71) SIGNAL 1 CIRCUIT FOR A SHORT TO VOLTAGE 
    WARNING:

    Turn the ignition off disconnect the 12-volt battery and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.

    WARNING:

    Do not place an intact non-deployed airbag face down on a hard surface, the airbag propels into the air if accidentally deployed. Failure to follow these instructions may result in possible serious or fatal injury.

    1. Turn the ignition off.
    2. Disconnect the Speed Control Switch harness connector.
    3. Turn the ignition on.
    4. Measure the voltage on the S/C (V71) Signal 1 circuit in the Speed Control Switch harness connector.

      Is the voltage above 5.6 volts?

      Yes 

      • Repair the short to voltage in the S/C (V71) Signal 1 circuit.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go to 3
  3. VISUALLY INSPECT THE SPEED CONTROL SWITCH HARNESS AND WIRING 
    1. Turn the ignition off.
    2. Visually and physically inspect the wiring harness between the Speed Control Switch harness connector.

      Were there any problems found?

      Yes 

      • Replace the Speed Control Switch in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go to 4
  4. CHECK THE S/C SWITCH CIRCUITS FOR AN OPEN/HIGH RESISTANCE BETWEEN THE SPEED CONTROL SWITCH AND CLOCKSPRING 
    1. Disconnect the Clockspring C2 harness connector.
    2. Measure the resistance of the:
      • S/C (V71) Signal 1 circuit between the Speed Control Switch harness connector and the Clockspring C2 harness connector.
      • S/C Switch Return circuit between the Speed Control Switch harness connector and the Clockspring C2 harness connector.

      Is the resistance below 3.0 Ohms for both circuits?

      Yes 

      • Go to 5

      No 

      • Repair the S/C circuit that measured above 3.0 Ohms for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  5. CHECK THE CLOCKSPRING 
    1. Disconnect the Clockspring C1 harness connector.
      NOTE:

      Measure at the Clockspring terminals, not the harnesses.

    2. Measure the resistance through the Clockspring:
      • Measure the resistance of the S/C (V71) Signal 1 circuit between the Clockspring C1 connector and the Clockspring C2 connector.
      • Measure the resistance of the S/C Switch Return circuit between the Clockspring C1 connector and the Clockspring C2 connector.

      Is the resistance below 3.0 Ohms for both circuits?

      Yes 

      • Go to 6

      No 

      • Replace the Clockspring harness in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  6. CHECK THE S/C SWITCH CIRCUITS FOR AN OPEN/HIGH RESISTANCE BETWEEN THE CLOCKSPRING AND BODY CONTROL MODULE 
    1. Disconnect the BCM C4 harness connector.
    2. Measure the resistance of the:
      • S/C (V71) Signal 1 circuit between the Clockspring C1 harness connector and the BCM C4 harness connector.
      • S/C Switch Return circuit between the Clockspring C1 harness connector and the BCM C4 harness connector.

      Is the resistance below 3.0 Ohms for both circuits?

      Yes 

      • Go to 7

      No 

      • Repair the S/C circuit that measured above 3.0 Ohms for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  7. CHECK THE ABILITY OF THE BCM TO DETECT THE SPEED CONTROL SWITCH 
    1. Reconnect all disconnected harness connectors.
    2. With the scan tool, monitor the Speed Control Switch voltage signal.
      NOTE:

      If the reading is not available on the scan tool, back probe and measure the voltage on the S/C (V71) Signal 1 circuit at the Speed Control Switch harness connector.

    3. Turn the Speed Control Switch On/Off switch to On.
    4. Press the other Speed Control functions.
      NOTE:

      The signal voltage should read 5.0 volts when the switch is off. The voltage should change between 0 volts and 5.0 volts when turned on and the speed control buttons are pressed.

      Is the Speed Control Switch voltage signal changing as described above?

      Yes 

      • Go to 8

      No 

      • Replace the Speed Control Switch in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  8. CHECK RELATED BCM AND COMPONENT CONNECTIONS 
    1. Disconnect all BCM harness connectors.
    2. Disconnect all related in-line harness connections (if equipped).
    3. Disconnect the related component harness connectors.
    4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
      • Proper connector installation.
      • Damaged connector locks.
      • Corrosion.
      • Other signs of water intrusion.
      • Weather seal damage (if equipped).
      • Bent terminals.
      • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
      • Terminals that have been pushed back into the connector cavity.
      • Check for spread terminals and verify proper terminal tension.

      Repair any conditions that are found.

    5. Reconnect all BCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    7. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. With the scan tool, erase DTCs.
    9. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
    10. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      No 

      • The wiring or poor connection problem has been repaired.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
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