P0592

SYMPTOM
P0592-SPEED CONTROL SWITCH 2 CIRCUIT LOW

WHEN MONITORED
With the ignition key on.

SET CONDITION
Speed control switch input No.2 is below the minimum acceptable voltage at the PCM. One trip fault.

POSSIBLE CAUSES
- (V38) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO GROUND
- (V38) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO THE (V937) SWITCH RETURN CIRCUIT
- CLOCKSPRING
- SPEED CONTROL RESUME/ACCEL SWITCH
- SPEED CONTROL ON/OFF SWITCH
- PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Scan Tool Testing and Procedures

DIAGNOSTIC TEST
1. SPEED CONTROL SWITCH VOLTAGE LOW





Note: 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>> 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 4.7 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 4.7 volts?
Yes>> Replace the Speed Control Resume/Accel Switch. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 4

4. CLOCKSPRING





Turn the ignition off.
Disconnect the clockspring harness connector (instrument panel wiring side) 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 (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 5

5. (V38) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO GROUND





Turn the ignition off.
Connect the Clockspring harness connectors per Service Information.
Disconnect the PCM harness connectors.

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 between ground and the (V38) S/C Switch No.2 Signal circuit to the appropriate terminal of special tool # 8815.
Is the resistance below 100 ohms?
Yes>> Repair the short to ground in the (V38) S/C Switch No.2 Signal circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 6

6. (V38) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO THE (V937) SWITCH RETURN CIRCUIT





Measure the resistance between the (V937) Switch Return circuit and the (V38) S/C Switch No.2 Signal circuit in the Speed Control Switch.
Is the resistance below 5.0 ohms?
Yes>> Repair the short between the (V38) S/C Switch No.2 Signal circuit and the (V937) Switch Return circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 7

7. 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 (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 8.

8. 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.