P0579
P0579-SPEED CONTROL SWITCH 1 PERFORMANCE
For a complete wiring diagram refer to Diagrams/Electrical.
- When Monitored:
With the ignition key on.
- Set Condition:
Cruise 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.
Diagnostic Test
1. ACTIVE DTC
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 DTC Active at this time?
Yes
- Go To 2
No
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
2. SPEED CONTROL SWITCH
Turn the ignition off.
Remove and disconnect the Speed Control Switch from the steering wheel.
Measure the resistance across each Speed Control Switch.
Monitor the ohmmeter while pressing each function button on the switch.
The following resistance specs are taken between terminals (V71) S/C Signal 1 and (V937) S/C 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 - 5.49k ohms
Coast - 2.94k ohms
Cancel - 1.24k ohms
Resume/Accel - 15.4k ohms
Does the function on the Speed Control Switches have the correct resistance value?
Yes
- Go To 3
No
- Replace the Speed Control Switch that had the incorrect resistance value.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
3. (V71) S/C SIGNAL 1 CIRCUIT SHORTED TO VOLTAGE
Disconnect the C3 PCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (V71) S/C Signal 1 circuit in the S/C Switch harness connector.
Is there any voltage present?
Yes
- Repair the short to voltage in the (V71) S/C Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 4
4. (V71) S/C SIGNAL 1 CIRCUIT OPEN
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 Miller Special Tool #8815 to perform diagnosis.
Turn the ignition off.
Measure the resistance of the (V71) S/C Signal 1 circuit from the Speed Control Switch to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms for each measurement?
Yes
- Go To 5
No
- Repair the open in the (V71) S/C Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
5. (V937) S/C RETURN CIRCUIT OPEN
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 Miller Special Tool #8815 to perform diagnosis.
Measure the resistance of the (V937) S/C Return circuit from the S/C Switch harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
- Go To 6
No
- Repair the open in the (V937) S/C Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
6. (V71) S/C SIGNAL 1 CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (V71) S/C Signal 1 circuit in the S/C Switch harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short to ground in the (V71) S/C Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 7
7. (V71) S/C SIGNAL 1 CIRCUIT SHORTED TO THE (V937) S/C RETURN CIRCUIT
Measure the resistance between the (V71) S/C Signal 1 circuit and the (V937) S/C Return circuit in the S/C Switch harness connector.
Is the resistance below 5.0 ohms?
Yes
- Repair the short between the (V71) S/C Signal 1 circuit and the (V937) S/C Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 8
8. SPEED CONTROL SWITCH VOLTAGE VALUES
Allow the engine to idle.
With a scan tool, monitor the S/C Switch voltage readings.
Take these same voltage measurements with a voltmeter by back probing the (V71) S/C Signal 1 circuit and the (V72) S/C Signal 2 circuit at the switches.
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 of a 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 9
9. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
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