P0580
SYMPTOM
P0580-SPEED CONTROL SWITCH 1 CIRCUIT LOW (5.7L)
WHEN MONITORED
With the ignition key on.
SET CONDITION
Speed control switch input No.1 is below the minimum acceptable voltage at the PCM. One trip fault.
POSSIBLE CAUSES
- (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN
- (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
- CLOCKSPRING
- SPEED CONTROL ON/OFF SWITCH
- SPEED CONTROL RESUME/ACCEL SWITCH
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Scan Tool Testing and Procedures
DIAGNOSTIC TEST
1. SPEED CONTROL SWITCH VOLTAGE LOW
Note: Do not press any of the Speed Control Switch buttons.
Ignition on, engine not running.
With a scan tool, read the Speed Control voltage.
Is the Speed Control voltage below 1.0 volt?
Yes>> Go To 2
No>> Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4. Powertrain Verification Test - Ver 4
2. SPEED CONTROL SWITCHES
Turn the ignition off.
Remove and disconnect the Speed Control Switches from the steering wheel per Service Information.
Measure the resistance across each Speed Control Switch.
Monitor the ohmmeter while pressing each function button on each switch.
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 positions.
Not pressing any switch - 20.5 k ohms
On/Off- 0.47 k ohms
Set- 5.49 k ohms
Coast- 2.94 k ohms
Cancel- 1.24 k ohms
Resume/Accel - 15.4 k 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 (NGC) POWERTRAIN VERIFICATION TEST VER-4.
3. SPEED CONTROL ON/OFF SWITCH
Connect the Resume/Accel Switch. Ignition on, engine not running. With the scan tool, monitor the Speed Control Switch voltage. Disconnect the Speed Control On/Off Switch harness connector.
Did the voltage change to above 4.8 volts?
Yes>> Replace the Speed Control On/Off Switch. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 4
4. SPEED CONTROL RESUME/ACCEL SWITCH
With the scan tool, monitor the Speed Control Switch voltage. Disconnect the Speed Control Resume/Accel Switch harness connector per Service Information.
Did the voltage change to above 4.8 volts?
Yes>> Replace the Speed Control Resume/Accel Switch. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 5
5. CLOCKSPRING
Turn the ignition off. Disconnect the clockspring harness connector (instrument panel wiring side) per Service Information. Ignition on, engine not running. With the scan tool, read the S/C Switch voltage.
Did the S/C Switch volts change to 5.0 volts?
Yes>> Replace the Clockspring. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 6
6. (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT
Turn the ignition off.
Connect the Clockspring harness connectors per Service Information.
Disconnect the PCM 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 Miller Special Tool # 8815 to perform diagnosis.
Measure the resistance between the (V937) S/C Switch Return circuit and the (V37) S/C Switch No.1 Signal circuit at the Speed Control Switch.
Is the resistance below 5.0 ohms?
Yes>> Repair the short between the (V37) S/C Switch No.1 Signal circuit and the (V937) S/C Switch Return circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 7
7. (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (V37) S/C Switch No.1 Signal circuit in the Switch 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 (NGC) POWERTRAIN VERIFICATION TEST VER-4.
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 (V37) S/C Switch No.1 Signal 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 (NGC) POWERTRAIN VERIFICATION TEST VER-4.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Replace and program the Powertrain Control Module per Service Information. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.