P0581-SPEED CONTROL SWITCH 1 CIRCUIT HIGH
For a complete wiring diagram Refer to Section 8W.
- When Monitored:
With the ignition key on.
- Set Condition:
Speed control switch input above the maximum acceptable voltage at the PCM. One trip fault.
| Possible Causes |
| (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE |
| (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT OPEN |
| (K914) SWITCH RETURN CIRCUIT OPEN |
| CLOCKSPRING |
| SPEED CONTROL 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 HIGHNOTE: 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 above 4.8 volts?
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.
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 (K914) S/C Switch Return circuits of the Switch when holding the switch button in the following position
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. CLOCKSPRING
Disconnect the C1 and C4 Clockspring harness connector per Service Information.
Measure the resistance of the (K914) Switch Return circuit between the C1 and C4 Clockspring harness connectors.
Measure the resistance of the (V37) S/C Switch No.1 Signal circuit between the C1 and C4 Clockspring harness connectors.
Was the resistance above 5.0 ohms for either circuit?
Yes
- Replace the Clockspring.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 4
4. (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Connect the Clockspring harness connectors per Service Information.
Disconnect the C4 PCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (V37) S/C Switch No.1 Signal circuit in the Speed Control harness connector.
Is the voltage above 0 volts?
Yes
- Repair the short to battery voltage in the (V37) S/C Switch No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 5
5. (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT OPEN
NOTE: The measurement must be taken from both Speed Control Switch harness connectors.
Turn the ignition off.
Disconnect the C4 Clockspring harness connector.
Measure the resistance of the (V37) S/C Switch No.1 Signal circuit from the S/C Switch harness connectors to the C4 Clockspring harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 6
No
- Repair the open in the (V37) S/C Switch No.1 Signal circuit between the Switch and Clockspring
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
6. (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT OPEN
Disconnect the C1 Clockspring harness connector
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 (V37) S/C Switch No.1 Signal circuit from the C1 Clockspring harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms for both measurements?
Yes
- Go To 7
No
- Repair the open in the (V37) S/C Switch No.1 Signal circuit between the Clockspring and PMC
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
7. (K914) SWITCH RETURN CIRCUIT OPEN
NOTE: The measurement must be taken from both Speed Control Switch harness connectors.
Measure the resistance of the (K914) Switch Return circuit from the S/C Switch harness connector to the C4 Clockspring harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 8
No
- Repair the open in the (K914) Switch Return circuit between the Switch and Clockspring.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
8. (K914) SWITCH RETURN CIRCUIT OPEN
Measure the resistance of the (K914) Switch Return circuit from the C1 Clockspring harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms for both measurements?
Yes
- Go To 9
No
- Repair the open in the (K914) Switch Return circuit between the Clockspring and PCM.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
9. 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 (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 the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 10
10. 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)