P0579

P0579-SPEED CONTROL SWITCH 1 PERFORMANCE

Special Tools:










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

Theory of Operation

The Speed Control Switch is hardwired to the Steering Column Control Module (SCCM). The SCCM is located near the top of the steering column below the steering wheel. The SCCM includes the steering column shroud, the Steering Angle Sensor (SAS), the Clockspring, the Multi-function Switch, a Steering Column Power Tilt and Telescope Switch (if equipped), and a trim cover.

- When Monitored:
With the ignition switch on and no other S/C Switch DTCs present.

- Set Condition:
The S/C Switch Signal 2 voltage is not within a valid switch signal range.





1. DTC IS ACTIVE
1. Turn the ignition on.
2. With the scan tool, select View DTCs. Copy DTC and Freeze Frame information.

NOTE: This DTC is a two trip fault. If the scan tool indicates a one trip failure, the possible cause may have been the customer pressing switches simultaneously. Test drive the vehicle and activate the Speed Control system. If the DTC matures to an active fault a repair is necessary.

3. With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

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

2. CHECK FOR HIGH RESISTANCE IN THE SPEED CONTROL SWITCH CIRCUITS

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 to perform diagnosis.

1. Turn the ignition off.
2. Disconnect the Speed Control Switch harness connector.
3. Disconnect the PCM C3 Harness connector.
4. Measure the resistance of the (V38) S/C Signal 2 circuit between the appropriate terminal of the PCM Pinout Box and Speed Control Switch harness connector.
5. Measure the resistance of the (V937) Switch Return circuit between the appropriate terminal of the PCM Pinout Box and Speed Control Switch harness connector.

Is the resistance below 5.0 Ohms for both measurements?

Yes

- Go To 3

No

- Go To 5

3. SPEED CONTROL SWITCH
1. Turn the ignition off.
2. Disconnect the Speed Control Switch harness connector.
3. Measure the resistance between the (V72) S/C Signal 2 terminal and the (V937) S/C Switch Return terminal at the Speed Control Switch, not the harness connector.
4. Monitor the Ohmmeter while pressing each function button on each switch.
5. The following resistance specs are taken between terminals (V72) S/C Signal 2 terminal and the (V937) Switch Return terminal 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 4

No

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

4. POWERTRAIN CONTROL MODULE
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Speed Control Switch and the Powertrain Control Module.
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

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

No

- Replace and program the Powertrain Control Module (PCM). Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. STEERING WHEEL JUMPER HARNESS
1. Turn the ignition off.
2. Disconnect the Clockspring C8 harness connector.
3. Measure the resistance of the (V38) S/C Signal 2 circuit between the Clockspring C8 harness connector and Speed Control Switch harness connector.
4. Measure the resistance of the (V937) Switch Return circuit between the Clockspring C8 harness connector and Speed Control Switch harness connector.

Is the resistance below 5.0 Ohms for both measurements?

Yes

- Go To 6

No

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

6. CLOCKSPRING
1. Disconnect the Clockspring C2 harness connector.
2. Measure the resistance of the (V38) S/C Signal 2 circuit between the C2 and C8 Clockspring connections.

3. Measure the resistance of the (V937) Switch Return circuit between the C2 and C8 Clockspring harness connectors.

Is the resistance below 5.0 Ohms for both measurements?

Yes

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

No

- Repair the circuit that measured above 5.0 Ohms for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.