P0592

P0592-SPEED CONTROL SWITCH 2 CIRCUIT LOW





For a complete wiring diagram Refer to Diagrams/Electrical.


- 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.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.


Diagnostic Test


1. ACTIVE DTC
Start the engine and allow it to idle for at least 60 seconds.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.


NOTE: It may be necessary to test drive the vehicle and operate the speed control in order for this DTC to set.

With a scan tool, select View DTCs.
Is the DTC Active at this time?

Yes


- Go To 2


No


- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition




2. SPEED CONTROL SWITCH
With the scan tool, monitor the Speed Control Switch voltage.
Disconnect the Speed Control Switch harness connector.
Did the voltage change to above 4.7 volts?

Yes


- Replace the Speed Control Switch.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 3




3. (V72) S/C SIGNAL 2 CIRCUIT SHORTED TO GROUND




Turn the ignition off.
Disconnect the C3 PCM harness connector.
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 4




4. (V72) S/C SIGNAL 2 CIRCUIT SHORTED TO THE (V937) S/C SWITCH GROUND CIRCUIT




Measure the resistance between the (V72) S/C Signal 2 circuit and the (V937) S/C Switch Ground 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 Switch Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 5




5. EXCESSIVE RESISTANCE IN THE (V72) S/C SIGNAL 2 CIRCUIT




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 Speed Control Switch to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms for each measurement?

Yes


- Go To 6


No


- Repair the excessive resistance in the (V72) S/C Signal 2 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test




6. SPEED CONTROL SWITCH VOLTAGE VALUES
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 and #8815-1 to perform diagnosis.

Using a voltmeter check the voltage on the (V38) S/C Signal 2 circuit at the appropriate terminals of the special tool #8815.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Start the engine and allow it to reach normal operating temperature.
Monitor the voltmeter.
Allow the engine to idle.
With a scan tool, monitor the S/C Switch voltage readings.






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


- Verify that there is good pin to terminal contact in the Switches and Powertrain Control Module connectors. Replace the Speed Control Switch if no problems were found in the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 7




7. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Speed Control Switch and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Switch and Powertrain Control Module connectors.
Refer to any Technical Service Bulletins that may apply.
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