P0480-COOLING FAN 1 CONTROL CIRCUIT/OPEN
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. The fan receives a duty cycle signal from the Totally Integrated Power Module (TIPM) on the Radiator Fan Speed Control circuit. 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 connections and may set a DTC if the Cooling Fan Relays are removed or damaged.
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When Monitored:
With the ignition on. Battery voltage greater than 10 volts.
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Set Condition:
The Powertrain Control Module (PCM) is requesting the Totally Integrated Power Module (TIPM) to turn on the Cooling Fan On and it is not operating.
Possible Causes |
|---|
| CAN BUS FAILURE |
| ENGINE COOLANT TEMP (ECT) SENSOR DTCS SET |
| COOLING FAN CONTROL CIRCUIT DTCS SET IN THE TIPM |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
1. COOLING FAN RELAY OPERATION
| 1. | Ignition on, engine not running. |
| 2. | With a scan tool, actuate the Cooling Fan. |
Is the Cooling Fan operating?
Yes
- Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
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. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Diagnosis and Testing).
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. (Refer to 28 - DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Diagnosis and Testing).
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 Totally Integrated Power Module (TIPM) 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. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Replace and program the Powertrain Control Module in accordance with the Service Information. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Powertrain Control - Removal) .
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).