P0591
P0591-SPEED CONTROL SWITCH 2 PERFORMANCEP0591-Speed Control Switch 2 Performance:
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.
POSSIBLE CAUSES
- (V372) S/C switch no.2 signal circuit open
- (V72) S/C switch no.2 signal circuit open
- (V372) S/C switch no.2 signal circuit shorted to battery voltage
- (V72) S/C switch no.2 signal circuit shorted to battery voltage
- (V397) Switch return circuit open
- (V937) Switch return circuit open
- (V372) S/C switch no.2 signal circuit shorted to ground
- (V72) S/C switch no.2 signal circuit shorted to ground
- (V372) S/C switch no.2 signal circuit shorted to the (V397) switch return circuit
- (V72) S/C switch no.2 signal circuit shorted to the (V937) switch return circuit
- Speed control switch
- SCCM
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. SPEED CONTROL SWITCH STATUS
Start the engine.
With a scan tool, monitor each which function for the Speed Control Switches.
Press and release each Speed Control Button.
- Resume/Accel
- Cancel
- Decel (Coast)
- On/Off
- Set
Q: Does each switch function change status when pressing and then depressing each switch?
YES: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Component Tests and General Diagnostics
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 2
2. SPEED CONTROL SWITCHES
Turn the ignition off.
Remove 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 (V372) S/C Switch No.2 Signal and (V397) 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 - 8.87 kohms
Set - 0.825 kohms
Coast - 0.47 kohms
Cancel - 3.92 kohms
Resume/Accel - 1.87 kohms
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 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
Q: 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. (V372) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Disconnect the C3 PCM harness connector.
Disconnect the C3 Steering Column Control Module harness connector.
Ignition on, engine not running.
Measure the voltage of the (V372) S/C Switch No.2 Signal circuit in the S/C Switch harness connectors.
Q: Is the voltage above 0 volts?
YES: Repair the short to battery voltage in the (V372) S/C Switch No.2 Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 4
4. (V72) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Disconnect the C1 Steering Column Control Module harness connector.
Ignition on, engine not running.
Measure the voltage on the (V72) S/C Switch No.2 Signal circuit in the C1 SCCM harness connector.
Q: Is the voltage above 0 volts?
YES: Repair the short to battery voltage in the (V72) S/C Switch No.2 Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 5
5. STEERING COLUMN CONTROL MODULE
Turn the ignition off.
Measure the resistance of the (V372) S/C Switch No.2 Signal circuit between the C1 and C3 SCCM connections.
Measure the resistance of the (V397) Switch Return circuit between the C1 and C3 SCCM connections.
Q: Is the resistance above 5.0 ohms?
YES: Replace the Steering Column Control Module. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 6
6. (V372) S/C SWITCH NO.2 SIGNAL CIRCUIT OPEN
NOTE: The measurement must be taken from both Speed Control Switch harness connectors.
Measure the resistance of the (V372) S/C Switch No.2 Signal circuit from both Speed Control harness connectors to the C3 SCCM harness connector.
Q: Is the resistance below 5.0 ohms for both measurements?
YES: Go To 7
NO: Repair the open in the (V372) S/C Switch No.2 Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
7. (V72) S/C SWITCH NO.2 SIGNAL 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 (V72) S/C Switch No.2 Signal circuit from the C1 SCCM harness connector to the appropriate terminal of special tool #8815.
Q: Is the resistance below 5.0 ohms for both measurements?
YES: Go To 8
NO: Repair the open in the (V72) S/C Switch No.2 Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
8. (V397) SWITCH RETURN CIRCUIT OPEN
Measure the resistance of the (V397) Switch Return circuit from the S/C Switch harness connectors to the C3 SCCM harness connector.
Q: Is the resistance below 5.0 ohms for both measurements?
YES: Go To 9
NO: Repair the open in the (V397) Switch Return circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
9. (V937) SWITCH RETURN OPEN
Measure the resistance of the (V397) Switch Return circuit from the C1 SCCM harness connector to the appropriate terminal of special tool #8815.
Q: Is the resistance below 5.0 ohms for both measurement?
YES: Go To 10
NO: Repair the open in the (V937) Switch Return circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
10. (V372) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (V372) S/C Switch No.2 Signal circuit in the Speed Control harness connectors.
Q: Is the resistance below 100 ohms?
YES: Repair the short to ground in the (V372) S/C Switch No.2 Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 11
11. (V72) S/C NO.2 SWITCH SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (V72) S/C Switch No.2 Signal circuit in the C1 SCCM harness connector.
Q: Is the resistance below 100 ohms?
YES: Repair the short to ground in the (V72) S/C Switch No.2 Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 12
12. (V372) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO THE (V397) SWITCH RETURN CIRCUIT
Measure the resistance between the (V372) S/C Switch No.2 Signal circuit and the (V397) Switch Return circuit in the Speed Control harness connector.
Q: Is the resistance below 5.0 ohms?
YES: Repair the short between the (V372) S/C Switch No.2 Signal circuit and the (V397) Switch Return circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 13
13. (V72) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT
Measure the resistance between the (V72) S/C Switch No.2 Signal circuit and the (V937) S/C Switch Return circuit in the C1 SCCM harness connector.
Q: Is the resistance below 5.0 ohms?
YES: Repair the short between the (V72) S/C Switch No.2 Signal circuit and the (V937) Switch Return circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 14
14. 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 (V371) S/C Switch No.1 Signal circuit and the (V372) S/C Switch No.2 Signal circuit at the switches.
Compare the voltage readings on the voltmeter to what the scan tool displayed.
Q: 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 values?
YES: Replace the Speed Control Switch. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 15
15. 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.
Q: 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