P0483 FAN SPEED

When Monitored and Set Condition:

When Monitored: While the engine is running.
Set Condition: The actual fan speed is less than 75 RPM or more than 4000 RPM.

POSSIBLE CAUSES

• OTHER DTC'S
• (Y5) SIGNAL CIRCUIT SHORT TO 5-VOLT SUPPLY (Y3) CIRCUIT
• (Y5) SIGNAL CIRCUIT OPEN FROM ECM TO FAN CLUTCH ASSEMBLY
• (Y3) SUPPLY CKT OPEN FROM ECM HARNESS CONNECTOR TO FAN CLUTCH HARNESS
• CONNECTOR
• INTERMITTENT CONDITION
• (Y5) SIGNAL CIRCUIT SHORTED TO RETURN IN THE HARNESS
• (Y5) SIGNAL CIRCUIT SHORTED TO VOLTAGE
• (Y5) SIGNAL CIRCUIT IN ECM SHORTED TO GROUND INSIDE ECM
• (Y5) SIGNAL CIRCUIT SHORTED TO VOLTAGE IN THE ECM
• (Y3) 5-VOLT SUPPLY CIRCUIT IN ECM

DIAGNOSTIC PROCEDURE

1. With the DRBIII®, read DTCs. Is DTC P0480 present?
   Yes --> Repair other DTCs first. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 2
2. Disconnect the Fan clutch connector
   NOTE: Check connectors - Clean/repair as necessary.
   Measure the resistance between the (Y5) signal circuit in the fan clutch assembly and the battery (Y3) 5-volt supply circuit in the fan clutch assembly. Is the resistance less than 10 Ohms?
   Yes --> Replace the Fan clutch assembly. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 3
3. Disconnect the ECM harness connectors. Check connectors - Clean/repair as necessary. Measure the resistance of the (Y5) signal circuit between the ECM harness connector and the fan clutch assembly harness connector. Is the resistance less than 10 Ohms?
   Yes --> Go To 4
   No --> Repair the open (Y5) circuit from the ECM harness connector to the Fan clutch harness connector. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
4. Measure the resistance of the (Y3) 5-volt supply circuit between the ECM harness connector and the fan clutch assembly harness connector. Is the resistance less than 10 Ohms?
   Yes --> Go To 5
   No --> Repair the open (Y5) circuit from ECM harness connector to Fan clutch connector. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
5. Measure the resistance between the (Y5) signal circuit in the fan clutch assembly harness connector and the return circuit in the fan clutch assembly harness connector. Is the resistance less than 10 Ohms?
   Yes --> Repair the shorted (Y5) circuit. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 6
6. Measure the voltage between the (Y5) signal circuit in the fan clutch assembly harness connector and battery negative. Is the voltage greater than 1 volt?
   Yes --> Repair the (Y5) signal circuit shorted to voltage. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 7
7. Reconnect the ECM harness connectors. Measure the resistance between the (Y5) signal circuit in the fan clutch assembly harness connector and battery negative. Is the resistance less than 10 Ohms?
   Yes --> Replace the ECM. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 8
8. Reconnect the fan harness connector. Turn the ignition on. While back probing the fan connector measure the voltage between the fan speed (Y5) signal circuit in the fan clutch assembly harness connector and battery negative while manually rotating the fan blade. Did voltage go from less than 0.7 volts to 4.7 to 5.7 volts?
   Yes --> Repair the Fan Speed (Y5) Signal circuit in the engine harness. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 9
9. Turn the ignition on. Measure the voltage between the (Y3) 5-volt supply circuit in the fan clutch assembly harness connector and battery negative. Is the voltage between 4.5 and 5.5 volts?
   Yes --> Refer to the SYMPTOM: INTERMITTENT CONDITION Symptom (Diagnostic Procedure). Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Replace the ECM. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).