P0483
P0483-COOLING FAN SPEED
For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.
Theory of Operation
The cooling fan is a hydro-electric controlled device that is engine mounted. The ECM monitors various sensors to control fan speed. The cooling fan provides temperature control for engine coolant, engine charged air, A/C Freon and automatic transmission fluid. Fan speed increases as cooling requirements increase. Since the fan is mounted to the engine, fan speed is related to engine speed (RPM). The ECM uses a Pulse Width Modulated (PWM) driver to control the amount of fluid to the clutch fan. When the fan is fully engaged it is capable of speeds about 10% greater than engine speed. The fan will rotate anytime the engine is running, even when the ECM is not sending a PWM signal.
- When Monitored:
While the engine is running.
- Set Condition:
The actual fan speed is less than 50 RPM or more than 6000 RPM.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
1. ACTIVE DTC
NOTE: If any 5-Volt supply DTCs are present, repair those DTCs before proceeding.
1. Turn the ignition on.
2. Using the scan tool, record all Freeze frame data.
3. Using the scan tool, erase DTCs.
4. Turn the ignition off for 30 seconds.
5. Start the engine and let idle. It may be necessary to test drive vehicle.
6. Using the scan tool, read DTCs.
Did the DTC reset?
Yes
- Go To 2
No
- Perform the INTERMITTENT DTC diagnostic procedure.Intermittent Condition Test
2. (N27) FAN SPEED SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the Radiator Fan Assembly harness connector.
NOTE: Check connectors - Clean/repair as necessary.
3. Turn the ignition on.
4. Measure the voltage on the (N27) Fan Speed Sensor Signal circuit at the Clutch Fan Assembly harness connector.
Is there any voltage present?
Yes
- Repair the short to voltage in the (N27) Fan Speed Sensor Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Go To 3
3. (N27) FAN SPEED SENSOR SIGNAL CIRCUIT OPEN
1. Turn the ignition off.
2. Disconnect the ECM C1 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
3. Measure the resistance of the (N27) Fan Speed Sensor Signal circuit between the Radiator Fan harness connector and the ECM C1 harness connector.
Is the resistance less than 10.0 Ohms?
Yes
- Go To 4
No
- Repair the open or high resistance in the (N27) Fan Speed Sensor Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test
4. (K916) SENSOR GROUND CIRCUIT OPEN
1. Measure the resistance of the (K916) Sensor Ground circuit between the Radiator Fan harness connector and the ECM C1 harness connector.
Is the resistance less than 10.0 Ohms?
Yes
- Go To 5
No
- Repair the open or high resistance in the (K916) Sensor Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
5. (N27) FAN SPEED SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the (N27) Fan Speed Sensor Signal circuit at the Radiator Fan harness connector.
Is the resistance less than 10k Ohms?
Yes
- Repair the short to ground in the (N27) Fan Speed Sensor Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Go To 6
6. (N27) FAN SPEED SENSOR SIGNAL CIRCUIT SHORTED TO THE (K161) SENSOR GROUND CIRCUIT
1. Measure the resistance between the (N27) Fan Speed Sensor Signal circuit and the (K916) Sensor Ground circuit at the Radiator Fan harness connector.
Is the resistance below 10k Ohms?
Yes
- Repair the short between the (N27) Fan Speed Sensor Signal circuit and the (K916) Sensor Ground circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L). Powertrain Verification Test.
No
- Go To 7
7. RADIATOR FAN
1. Replace the Radiator Fan.
2. Turn the ignition on.
3. Using the scan tool, erase DTCs.
4. Turn the ignition off for 30 seconds.
5. Start the engine and let idle. It may be necessary to test drive vehicle.
6. Using the scan tool, read DTCs.
Did the DTC reset?
Yes
- Replace the Engine Control Module (ECM).
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Repair complete.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.