P0579

P0579-SPEED CONTROL SWITCH 1 PERFORMANCE

For a complete wiring diagram REFER to DIAGRAMS/ELECTRICAL

- When Monitored:
With the engine running and battery voltage greater than 10 volts.

- Set Condition:
The PCM detects that the input voltage is not within a specified range based on operating conditions.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

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

- Go to3

No

- Go to 2

2. DTC IS ACTIVE Turn the ignition off.

NOTE: Refer to the following table when diagnosing speed control switch voltage DTCs.

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

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Checking For An Intermittent DTC

No

- Go to3

3. SPEED CONTROL SIGNAL 1 VOLTAGE

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.
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

- Go to9

No

- Go to4

4. (V37) S/C SIGNAL 1 CIRCUIT SHORTED TO VOLTAGE

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

- Repair the (V37) S/C Signal 1 circuit for a short to voltage.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Go to 5

5. (V37) S/C SIGNAL 1 CIRCUIT SHORTED TO GROUND

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

- Go to 6

No

- Repair the (V37) S/C Signal 1 circuit for a short to ground.
- Perform the PCM Verification Test.Powertrain Verification Test

6. (V37) S/C SIGNAL 1 CIRCUIT SHORTED TO THE (V937) S/C SWITCH GROUND CIRCUIT

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

- Go to 7

No

- Repair the (V37) S/C Signal 1 circuit for a short to the (V937) S/C Switch Ground circuit.
- Perform the PCM Verification Test.Powertrain Verification Test

7. (V37) S/C SIGNAL 1 CIRCUIT OPEN OR HIGH RESISTANCE

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

- Go to10

No

- Repair the (V937) S/C Switch Ground circuit for an open circuit or high resistance.
- Perform the PCM Verification Test.Powertrain 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

- Repair as necessary.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Replace the Speed Control Switch.
- Perform the PCM Verification Test.Powertrain 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

- Repair as necessary.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification Test.Powertrain Verification Test