P0585
SYMPTOM
P0585-SPEED CONTROL SWITCH 1/2 CORRELATION (5.7L)
WHEN MONITORED
Ignition on.
SET CONDITION
Cruise Switch inputs are not coherent with each other. Example: PCM is reading Switch No.1 as Accel and Switch No.2 as Coast at the same time. One trip fault.
POSSIBLE CAUSES
- S/C SWITCH SIGNAL CIRCUITS SHORTED TO BATTERY VOLTAGE
- RESISTANCE IN THE S/C SWITCH SIGNAL CIRCUITS
- RESISTANCE IN THE (V937) SWITCH RETURN CIRCUIT
- S/C SWITCH SIGNAL CIRCUITS SHORTED TO THE (V937) SWITCH RETURN CIRCUIT
- (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO (V38) S/C SWITCH NO.2 SIGNAL CIRCUIT
- S/C SWITCH SIGNAL CIRCUITS 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. ACTIVE DTC
Ignition on, engine not running.
Note: This DTC may be the result of pressing two Speed Control Switch buttons simultaneously for more than 450 m sec.
Ask the customer if it is possible that two buttons were pressed at the same time before this DTC set. If this is the case, no repair is necessary.
Is the DTC active a this time?
Yes>> Go To 2
No>> Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4. Powertrain Verification Test - Ver 4
2. SPEED CONTROL ON/OFF SWITCH
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 3
3. SPEED CONTROL RESUME/ACCEL SWITCH
With the scan tool, monitor the Speed Control Switch voltage. Disconnect the Speed Control Resume/Accel Switch harness connector.
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 4
4. 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 (V38) S/C Switch No.2 Signal and (V937) S/C Switch Return circuits of the Switch when holding the switch button in the following position.
Not pressing any switch - 20.5 k ohms
On/Off- 8.87 k ohms
Set- 0.825 k ohms
Coast- 0.47 k ohms
Cancel - 3.92 k ohms
Resume/Accel - 1.87 k ohms
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 position
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 5
No>> Replace the Speed Control Switch that had the incorrect resistance value. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
5. S/C SWITCH SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Disconnect the PCM harness connectors. Measure the voltage on the (V37) and (V38) S/C Switch Signal circuits at both Speed Control harness connectors.
Is the voltage above 5.0 volts?
Yes>> Repair the short to battery voltage in the (V37) or (V38) S/C Switch Signal circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 6
6. CLOCKSPRING
Turn the ignition off.
Disconnect the upper and lower clockspring harness connectors per Service Information.
Measure the resistance of the (V37) and (V38) S/C Switch Signal circuits between the upper and lower clockspring harness connectors.
Measure the resistance of the (V937) Switch Return circuit between the upper and lower clockspring harness connectors.
Is the resistance above 5.0 ohms?
Yes>> Replace the Clockspring per Service Information. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 7
Note: Connect the Clockspring harness connectors per Service Information before continuing.
7. S/C SWITCH 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 (V37) and (V38) S/C Switch Signal circuits from both Speed Control harness connectors to the appropriate terminals of special tool # 8815.
Is the resistance below 5.0 ohms for each measurement?
Yes>> Go To 8
No>> Repair the excessive resistance in the (V37) or (V38) S/C Switch Signal circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
8. (V937) SWITCH RETURN CIRCUIT OPEN
Note: The measurement must be taken from both Speed Control Switch harness connectors.
Measure the resistance of the (V937) Switch Return circuit from both Speed Control 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 excessive resistance in the (V937) Switch Return circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
9. S/C SWITCH SIGNAL CIRCUITS SHORTED TO THE (V937) SWITCH RETURN CIRCUIT
Measure the resistance between the (V937) Switch Return circuit and both of the (V37) and (V38) S/C Switch Signal circuits in the Speed Control harness connector.
Is the resistance below 5.0 ohms?
Yes>> Repair the short between the (V937) Switch Return circuit and the (V37) or (V38) S/C Switch Signal circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 10
10. (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V38) S/C SWITCH NO.2 SIGNAL CIRCUIT
Measure the resistance between the (V37) S/C Switch No.1 Signal circuit and the (V38) S/C Switch No.2 Signal circuit at both Speed Control harness connectors.
Is the resistance below 100 ohms for each circuit?
Yes>> Repair the short between the (V38) S/C Switch No.2 Signal circuit and the (V37) S/C Switch No.1 Signal circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 11
11. S/C SWITCH SIGNAL CIRCUITS SHORTED TO GROUND
Measure the resistance between ground and the (V37) and (V38) S/C Switch Signal circuits at both Switch harness connectors.
Is the resistance below 100 ohms?
Yes>> Repair the short to ground in the (V37) or (V38) S/C Switch Signal circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 12
12. 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 and the (V38) S/C Switch No.2 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 values?
Yes>> Replace the Speed Control Switch. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 13
13. 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.