P0580 LOW VOLTAGE DETECTED AT THE SPEED CONTROL SWITCH

When Monitored and Set Condition:

When Monitored: While the ignition is on
Set Condition: Speed control MUX switch below 1.0 volts for 5 seconds.

POSSIBLE CAUSES

• S/C WIRING HARNESS OBSERVABLE PROBLEM
• S/C SWITCH (ON/OFF)
• CLOCKSPRING SHORTED TO GROUND
• S/C SWITCH (RESUME/ACCEL)
• S/C SWITCH SIGNAL CIRCUIT SHORTED TO GROUND
• S/C SIGNAL CIRCUIT SHORTED TO SENSOR GROUND
• ECM

DIAGNOSTIC PROCEDURE

1. Turn the ignition on. With the DRBIII®, read the S/C Switch volts status in the ECM. Is the S/C Switch voltage below 1.0 volt?
   Yes --> Go To 3
   No --> Go To 2
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. Turn the ignition off. Disconnect the S/C ON/OFF Switch harness connector.
   NOTE: Check connectors - Clean/repair as necessary.
   Turn the ignition on. With the DRBIII® in Sensors, read the S/C Switch volts in the ECM. Did the S/C Switch volts change to 5.0 volts?
   Yes --> Replace the S/C ON/OFF Switch. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
   No --> Go To 4
4. Turn the ignition off. Disconnect the S/C RESUME/ACCEL Switch harness connector.
   NOTE: Check connectors - Clean/repair as necessary.
   Ignition on, engine not running. With the DRBIII® in Sensors, read the S/C Switch volts in the ECM. Did the S/C Switch volts go above 4.0 volts?
   Yes --> Replace the Resume/Accel Switch. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
   No --> Go To 5
5. Turn the ignition off. Disconnect the clockspring 6-way harness connector (instrument panel wiring side). Turn the ignition on. With the DRBIII® in Sensors, read the S/C Switch volts in the ECM. Did the S/C Switch volts change to 5.0 volts?
   Yes --> Replace the Clockspring. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
   No --> Go To 6
6. Turn the ignition off. Disconnect the S/C ON/OFF Switch harness connector. Disconnect the ECM harness connectors.
   NOTE: Check connectors - Clean/repair as necessary.
   Measure the resistance between the S/C Switch Signal circuit and ground (B-) at S/C ON/OFF Switch harness connector. Is the resistance below 5.0 ohms?
   Yes --> Repair S/C Switch Signal Circuit for a short to ground. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
   No --> Go To 7
7. Measure the resistance between the S/C Signal Circuit and the Sensor Ground Circuit at the ON/OFF switch harness connector. Is the resistance below 5.0 ohms?
   Yes --> Repair S/C Signal Circuit shorted to Sensor Ground. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).
   No --> Replace and program the ECM in accordance with the Service Information. Perform POWERTRAIN VERIFICATION TEST VER - 4 (DIESEL).