P0481

P0481-COOLING FAN 2 CONTROL CIRCUIT

For a complete wiring diagram, refer to the Wiring Information.

Theory of operation

The Powertrain Control Module (PCM) sends a CAN bus message to the Totally Integrated Power Module (TIPM) requesting cooling fan operation. The TIPM grounds the coil for the requested Cooling Fan Relay through the radiator fan control circuit. The Cooling Fan Relay then provides battery voltage to the Cooling Fan Motor. Vehicles with diesel engines, certain export market vehicles and trailer tow packages are equipped with a pulse-width modulated (PWM) fan. Based on the requested fan speed from the PCM, the TIPM outputs a duty cycle signal on the Radiator Fan Speed Control circuit to the Radiator Cooling Fan. The Radiator Cooling Fan receives the duty cycle signal from the TIPM and controls the fan accordingly. The High or Low Speed Cooling Fan Relay is not used to control any components in a PWM system and have no external function. The TIPM connects to the Cooling Fan Relays through an internal connection and may set a DTC if the Cooling Fan Relays are removed or damaged.

- When Monitored:
With the ignition on. Battery voltage greater than 10.0 Volts.

- Set Condition:
The Powertrain Control Module (PCM) is requesting the Totally Integrated Power Module (TIPM) to turn on the Cooling Fan and it is not operating.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. COOLING FAN RELAY OPERATION
1. Ignition on, engine not running.
2. With the scan tool, actuate the Cooling Fan.

Is the Cooling Fan operating?

Yes

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

No

- Go To 2

2. CAN C or ECT DTCS CURRENTLY ACTIVE

Are any CAN C or ECT DTCs Active at this time?

Yes

- Perform the appropriate diagnostics for the ECT Sensor or CAN C Bus DTC. Testing and Inspection.

No

- Go To 3

3. COOLING FAN CONTROL CIRCUIT DTCS SET IN THE TIPM

Are any Cooling Fan Control Circuit DTCs set in the TIPM?

Yes

- Diagnose the appropriate Cooling Fan Control Circuit DTC in the TIPM. Testing and Inspection.

No

- Go To 4

4. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Engine Oil Pressure Sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Sensor and Powertrain Control Module connectors.
4. Perform 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. Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.