P0580-SPEED CONTROL SWITCH 1 CIRCUIT LOW
For a complete wiring diagram Refer to Section 8W.
- 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 |
| (V371) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V397) S/C SWITCH RETURN |
| (V71) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN |
| (V371) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND |
| (V71) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND |
| STEERING COLUMN CONTROL MODULE |
| SPEED CONTROL ON/OFF SWITCH |
| SPEED CONTROL RESUME/ACCEL SWITCH |
| PCM |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).
Diagnostic Test
1. SPEED CONTROL SWITCH VOLTAGE LOWNOTE: 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
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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 (V371) S/C Switch No.1 Signal and (V397) S/C Switch Return circuits of the Switch when holding the switch button in the following positions.
Not pressing any switch - 20.5 kohms
On/Off - 0.47 kohms
Set - 5.49 kohms
Coast - 2.94 kohms
Cancel - 1.24 kohms
Resume/Accel - 15.4 kohms
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. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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 the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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 the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 5
5. STEERING COLUMN CONTROL MODULE
Turn the ignition off.
Disconnect the C1 SCCM harness connector 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 the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 6
6. (V371) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V397) S/C SWITCH RETURN CIRCUIT
Turn the ignition off.
Disconnect the C3 SCCM harness connector.
Disconnect the C3 PCM harness connector.
Measure the resistance between the (V397) S/C Switch Return circuit and the (V371) S/C Switch No.1 Signal circuit at the S/C Switch harness connectors.
Is the resistance below 5.0 ohms?
Yes
- Repair the short between the (V371) S/C Switch No.1 Signal circuit and the (V397) S/C Switch Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 7
7. (V71) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT
Measure the resistance between the (V71) S/C Switch No.1 Signal circuit and the (V937) S/C Switch Return circuit in the C1 SCCM harness connector.
Is the resistance below 5.0 ohms?
Yes
- Repair the short between the (V71) S/C Switch No.1 Signal circuit and the (V937) Switch Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 8
8. (V371) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (V371) S/C Switch No.1 Signal circuit in the S/C Switch harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short to ground in the (V371) S/C Switch No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 9
9. (V71) S/C NO.1 SWITCH SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (V71) S/C Switch No.1 Signal circuit in the C1 SCCM harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short to ground in the (V71) S/C Switch No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 10
10. SPEED CONTROL SWITCH VOLTAGE VALUES
Allow the engine to idle.
With a scan tool, monitor the S/C Switch voltage readings.
| SWITCH POSITION | SWITCH No.1 VOLTAGE VALUE | SWITCH No.2 VOLTAGE VALUE |
| NO SWITCHES PRESSED | 4.31 to 4.78 volts | 4.31 to 4.78 volts |
| ON/OFF PRESSED | 0.59 to 1.13 volts | 3.53 to 3.92 volts |
| RES/ACCEL PRESSED | 3.88 to 4.17 volts | 2.04 to 2.47 volts |
| SET PRESSED | 3.16 to 3.56 volts | 1.17 to 1.56 volts |
| COAST PRESSED | 2.57 to 2.94 volts | 0.77 to 1.09 volts |
| CANCEL PRESSED | 1.59 to 1.99 volts | 2.84 to 3.25 volts |
Take these same voltage measurements with a voltmeter by back probing the (V371) 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 the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 11
11. 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. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Replace and program the Powertrain Control Module per Service Information.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)