P0579
P0579-SPEED CONTROL SWITCH 1 PERFORMANCE
For a complete wiring diagram, consult the Wiring Information.
- 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.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure
1. ACTIVE 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 may 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. With a scan tool, select View DTCs.
Is the DTC Active at this time?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. . Intermittent Condition Test
2. SPEED CONTROL SWITCH
1. Turn the ignition off.
2. Remove and disconnect the Speed Control Switches from the steering wheel.
3. Measure the resistance across each Speed Control Switch.
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 No.1 Signal and (V937) S/C Switch Return circuits 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. (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO VOLTAGE
1. Disconnect the C3 PCM harness connector.
2. Ignition on, engine not running.
3. Measure the voltage on the (V37) S/C Switch No.1 Signal circuit in the Speed Control harness connector.
Is there any voltage present?
Yes
- Repair the short to voltage in the (V37) S/C Switch No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 4
4. CLOCKSPRING
1. Turn the ignition off.
2. Disconnect the upper and lower clockspring harness connectors.
3. Measure the resistance of the (V37) S/C Switch No.1 Signal circuit between the upper and lower clockspring harness connectors.
4. Measure the resistance of the (V937) S/C Switch Return circuit between the upper and lower clockspring harness connectors.
Is the resistance above 5.0 Ohms?
Yes
- Replace the Clockspring.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 5 NOTE: Connect the Clockspring harness connectors before continuing.
5. (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT OPEN
NOTE: The measurement must be taken from both Speed Control Switch harness connectors.
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 PCM Pinout Box 8815 to perform diagnosis.
1. Measure the resistance of the (V37) S/C Switch No.1 Signal circuit from the Speed Control harness connector to the appropriate terminal of PCM Pinout Box 8815.
Is the resistance below 5.0 Ohms for both measurements?
Yes
- Go To 6
No
- Repair the open in the (V37) S/C Switch No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
6. (V937) S/C SWITCH RETURN CIRCUIT OPEN
NOTE: The measurement must be taken from both Speed Control Switch harness connectors.
1. Measure the resistance of the (V937) S/C Switch Return circuit from the Speed Control harness connector to the appropriate terminal of PCM Pinout Box 8815.
Is the resistance below 5.0 Ohms for both measurements?
Yes
- Go To 7
No
- Repair the open in the (V937) S/C Switch Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
7. (V37) S/C NO.1 SWITCH SIGNAL CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the (V37) S/C Switch No.1 Signal circuit in the Speed Control harness connector.
Is the resistance below 100 Ohms?
Yes
- Repair the short to ground in the (V37) S/C Switch No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 8
8. (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT
1. Measure the resistance between the (V37) S/C Switch No.1 Signal circuit and the (V937) S/C Switch Return circuit in the Speed Control harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Repair the short between the (V37) S/C Switch No.1 Signal circuit and the (V937) Switch Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 9
9. SPEED CONTROL SWITCH VOLTAGE VALUES
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 PCM Pinout Box 8815 and PCM Pinout Box Adapter 8815-1 to perform diagnosis.
1. Install the PCM Pinout Box 8815-1 on the C3 PCM harness connector.
2. Connect the S/C Switch harness connectors.
3. Connect the Clockspring harness connectors.
4. Turn the ignition on.
5. With a scan tool, monitor the S/C Switch voltage readings.
6. Using a voltmeter check the voltage on the (V37) S/C Switch No.1 Signal circuit and the (V38) S/C Switch No.2 Signal circuit at the appropriate terminals of the PCM Pinout Box 8815.
7. Monitor the voltmeter.
8. With a scan tool, monitor the S/C Switch voltage readings.
9. 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
- Verify that there is good pin to terminal contact in the Switch and Powertrain Control Module connectors. If OK, replace the Speed Control Switch.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 10
10. 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.