P0591
P0591-SPEED CONTROL SWITCH 2 PERFORMANCE
For complete wiring diagrams refer to Diagrams/Electrical.
- 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.
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 Switch.
Press and release each Speed Control Button.
- Resume/Accel
- Cancel
- Decel (Coast)
- On/Off
- Set
Does each switch function change status when pressing and then depressing each switch?
Yes
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 2
2. SPEED CONTROL SWITCHES
Turn the ignition off.
Remove the Speed Control Switch from the steering wheel.
Measure the resistance across the Speed Control Switch.
Monitor the ohmmeter while pressing each function button on the switch.
The following resistance specs are taken between terminals (V72) S/C Signal 2 circuit and (V937) S/C 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 (V71) S/C Signal 1 and (V937) S/C 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 Switch 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. (V72) S/C SIGNAL 2 CIRCUIT SHORTED TO BATTERY VOLTAGE
Disconnect the C3 PCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (V72) S/C Signal 2 circuit in the Switch harness connector.
Is the voltage above 0 volts?
Yes
- Repair the short to battery voltage in the (V72) S/C Signal 2 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 4
4. (V72) S/C SIGNAL 2 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 Signal 2 circuit from the Switch harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms for both measurements?
Yes
- Go To 5
No
- Repair the open in the (V72) S/C Signal 2 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
5. (V937) S/C RETURN OPEN
Measure the resistance of the (V937) S/C Return circuit from the Switch harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms for both measurement?
Yes
- Go To 6
No
- Repair the open in the (V937) S/C Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
6. (V72) S/C SIGNAL 2 CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (V72) S/C Signal 2 circuit in the Switch harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short to ground in the (V72) S/C Signal 2 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 7
7. (V72) S/C SIGNAL 2 CIRCUIT SHORTED TO THE (V937) S/C RETURN CIRCUIT
Measure the resistance between the (V72) S/C Signal 2 circuit and the (V937) S/C Return circuit in the Switch harness connector.
Is the resistance below 5.0 ohms?
Yes
- Repair the short between the (V72) S/C Signal 2 circuit and the (V937) S/C Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
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 (V71) S/C Signal 1 circuit and the (V72) S/C Signal 2 circuit at the switch.
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 values?
Yes
- Replace the Speed Control Switch.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
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 the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test