P0581 HIGH VOLTAGE DETECTED AT THE SPEED CONTROL SWITCH

When Monitored and Set Condition:

When Monitored: Key on or Engine running.
Set Condition: Speed Control MUX switch above 11.5 volts for 5 seconds.

POSSIBLE CAUSES

• S/C WIRING HARNESS OBSERVABLE PROBLEM
• CLOCKSPRING SIGNAL/GROUND CIRCUIT OPEN
• SPEED CONTROL ON/OFF SWITCH
• S/C SWITCH SIGNAL CKT SHORTED TO VOLTAGE
• S/C SWITCH SIGNAL CIRCUIT OPEN ECM TO CLOCK SPRING
• S/C SWITCH SIGNAL CIRCUIT OPEN CLOCKSPRING TO S/C SWITCH
• S/C SWITCH GROUND CIRCUIT OPEN CLOCKSPRING TO S/C SWITCH
• S/C SWITCH GROUND CIRCUIT OPEN ECM TO CLOCKSPRING
• ECM

DIAGNOSTIC PROCEDURE

1. Turn the ignition on. With the DRBIII® in Inputs/Outputs, read the Speed Control inputs state in ECM. While monitoring the DRBIII®, push the Speed Control On/Off Switch several times, then leave it on. Did the DRBIII® show Speed Control Switch off and on?
   Yes --> Go To 2
   No --> Test Complete.
2. Turn the ignition off. Using the Schematics as a guide, inspect the Wiring and Connectors. Were any problems found?
   Yes --> Repair as necessary. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
   No --> Go To 3
3. Disconnect the upper and lower 6-way clockspring harness connectors.
   NOTE: Check connectors - Clean/repair as necessary.
   Measure the resistance of the sensor ground circuit between the upper and lower 6-way clockspring harness connectors. Measure the resistance of the speed control switch signal circuit between the upper and lower 6-way clockspring harness connectors. Was the resistance above 5.0 ohms for either circuit?
   Yes --> Replace the clockspring. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
   No --> Go To 4
4. Disconnect the Speed Control On/Off Switch 2-way harness connector only.
   NOTE: Check connectors - Clean/repair as necessary.
   Measure the resistance across the S/C On/Off Switch. Is the resistance between 20.3K and 20.7K ohms?
   Yes --> Go To 5
   No --> Replace the On/Off Switch. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
5. Turn the ignition on. Measure the voltage of the S/C Switch Signal Circuit at the On/Off Switch 2-way connector. Is the voltage above 6.0 volts?
   Yes --> Repair the Speed Control Switch Signal Circuit for a short to voltage. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
   No --> Go To 6
6. Turn the ignition off. Disconnect the ECM harness connector.
   NOTE: Check connectors - Clean/repair as necessary.
   Measure the resistance of the S/C Switch Signal Circuit between the ECM connector and the Clockspring Connector. Is the resistance below 5.0 ohms?
   Yes --> Go To 7
   No --> Repair open Speed Control Switch Signal Circuit ECM to Clock-spring. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
7. Measure the resistance of the S/C Switch Signal Circuit from the clockspring harness connector to the On/Off switch harness connector. Is the resistance below 5.0 ohms?
   Yes --> Go To 8
   No --> Repair the open Speed Control Switch Signal Circuit Clockspring to S/C switch. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
8. Measure the resistance of the S/C Switch Sensor Ground Circuit between the On/Off Switch 2-way harness connector to the clockspring harness connector. Is the resistance below 5.0 ohms?
   Yes --> Go To 9
   No --> Repair open ground circuit from clockspring to S/C switch. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
9. Measure the resistance of the S/C Switch Sensor Ground Circuit between the ECM harness connector to the clockspring harness connector. Is the resistance below 5.0 ohms?
   Yes --> Replace and program the ECM in accordance with the Service Information. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
   No --> Repair open ground circuit from ECM to clockspring. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).