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Home >> Dodge or Ram Truck >> 2012 >> RAM 3500 Truck 2WD L6-6.7L DSL Turbo High Output >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0579

P0579






P0579-SPEED CONTROL SWITCH 1 PERFORMANCE

For a complete wiring diagram, refer to the Wiring Information.

- When Monitored:
With the ignition key on.

- Set Condition:
Speed Control (S/C) switch voltage output is not out of range but it does not equal any of the values for any of the button positions. One trip fault.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

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 can 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. Using the scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION - 6.7L diagnostic procedure. Intermittent Condition Test

2. SPEED CONTROL SWITCH
1. Turn the ignition off.
2. Disconnect the Speed Control Switch harness connector.
3. Measure the resistance between (V37) S/C Switch Sense 1 circuit and the (V937) Switch Return circuit.
4. Monitor the Ohmmeter while pressing each function button on each switch.
5. The following resistance specs are taken between terminals (V37) S/C Switch Sense 1 circuit and the (V937) Switch Return circuit of the switch when holding the switch button in the following position:
- Not pressing any switch - 20.5k Ohms
- On/Off - 0.47k Ohms
- Set/Decel - 4.34k Ohms
- Cancel - 1.24k Ohms
- Resume/Accel - 8.80k Ohms

Does the function on the Speed Control Switch have the correct resistance value +/- 0.2 Ohm?

Yes

- Go To 3

No

- Replace the Speed Control Switch.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. (V37) S/C SWITCH SENSE 1 CIRCUIT SHORTED TO VOLTAGE




1. Disconnect the Clockspring C2 harness connector.
2. Ignition on, engine not running.
3. Measure the voltage on the (V37) S/C Switch Sense 1 circuit at the Clockspring C2 harness connector.

Is the voltage reading above 5.2 volts?

Yes

- Repair the short to voltage in the (V37) S/C Switch Sense 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. (V37) S/C NO.1 SWITCH SIGNAL CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance between ground and the (V37) S/C Switch Sense 1 circuit at the Clockspring C2 harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 5

No

- Repair the short to ground in the (V37) S/C Switch Sense 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. (V37) S/C SWITCH SENSE 1 CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT




1. Measure the resistance between the (V37) S/C Switch Sense 1 circuit and the (V937) S/C Switch Return circuit at the Clockspring C2 harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 6

No

- Repair the short between the (V37) S/C Switch Sense 1 circuit and the (V937) Switch Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. CLOCKSPRING
1. Disconnect the Clockspring C8 harness connector.
2. Measure the resistance of the (V37) S/C Switch Sense 1 circuit between the Clockspring C2 and C8 at the Clockspring connectors.
3. Measure the resistance of the (V937) Switch Return circuit between the Clockspring C2 and C8 at the Clockspring connectors.

Is the resistance above 5.0 Ohms for either reading?

Yes

- Replace the Clockspring.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 7

7. STEERING WHEEL JUMPER HARNESS




1. Turn the ignition off.
2. Measure the resistance of the (V37) S/C Switch Sense 1 circuit between the Clockspring C8 harness connector and S/C Switch harness connector.
3. Measure the resistance of the (V937) Switch Return circuit between the Clockspring C8 harness connector and S/C Switch harness connector.

Is the resistance above 5.0 Ohms for either reading?

Yes

- Replace the Steering Wheel Jumper harness.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 8

8. (V37) S/C SWITCH SENSE 1 CIRCUIT OPEN/HIGH RESISTANCE
1. Measure the resistance of the (V37) S/C Switch Sense 1 circuit between the Clockspring C2 harness connector and the of PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 9

No

- Repair the open in the (V37) S/C Switch Sense 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

9. (V937) SWITCH RETURN CIRCUIT OPEN/HIGH RESISTANCE
1. Measure the resistance of the (V937) Switch Return circuit between the Clockspring C2 harness connector and the of PCM C2 harness connector.

Is the resistance below 5.0 Ohms ?

Yes

- Go To 10

No

- Repair the open in the (V937) Switch Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

10. SPEED CONTROL SWITCH VOLTAGE VALUES
1. Reconnect the S/C Switch harness connectors.
2. Reconnect the Clockspring harness connectors.
3. Reconnect the PCM C2 harness connector.
4. Back probe the (V37) S/C Switch Sense 1 circuit and the (V38) S/C Switch Sense 2 circuit at the PCM C2 harness connector.

CAUTION: Use only approved back probe tools when back probing a connector so as not to cause damage to the terminals or insulation of the connector. Damage to the terminals can cause poor terminal contact or retention. Damage to the insulation can introduce corrosion due to water infiltration.

5. Turn the ignition on.
6. Using the scan tool, monitor the S/C Switch voltage readings.
7. Using a Voltmeter check the voltage on the (V37) S/C Switch Sense 1 circuit and the (V38) S/C Switch Sense 2 circuit at the PCM C2 harness connector.
8. Monitor the Voltmeter.
9. Using the scan tool, monitor the S/C Switch voltage readings.





10. 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 Volt difference between the Voltmeter switch values and the scan tool switch value?

Yes

- Replace the Speed Control Switch.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 11

11. 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

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

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