Fix P0480: Mechanic’s solutions that WORKED

The code P0480: Cooling Fan 1 Control Circuit Malfunction indicates a malfunction in the control circuit of the engine cooling fan 1. It’s typically a sign that the fan isn’t operating as expected, which can stem from a variety of electrical issues, from a blown fuse to a faulty fan motor.

P0480 quick overview

Meaning	P0480: Cooling Fan 1 Control Circuit Malfunction
Is it serious?	Yes, it can lead to overheating and potential engine damage if not addressed promptly.
Possible causes	– Faulty cooling fan motor – Corroded or damaged fan motor connectors – Blown fuse for cooling fan circuit – Shorted or open wiring in the cooling fan circuit – Faulty cooling fan relay – Defective cooling fan control module – Issues with the engine control module (ECM)
How to diagnose?	Check for additional codes to see if there are related cooling system issues. Inspect cooling fan operation to confirm if the fan is running when it should be. Examine electrical connectors for the fan motor for signs of corrosion or damage. Measure resistance of the cooling fan motor to check for shorts or open circuits. Test the fan relay and replace if necessary. Inspect the fuse associated with the fan circuit for any blowouts. Review wiring harness for any shorts, frays, or breaks. Evaluate the control module if applicable, for proper operation. Consult a professional if the above steps do not resolve the issue.

How to fix P0480 – learn from mechanics

I looked into P0480 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Chevrolet

Vehicle Information 2005 Chevrolet Cobalt LS 2.2L with the MIL lamp on

Issue + Repair History

• MIL light on
• Cooling fan running at high speed when KOEO (Key On Engine Off) or KOER (Key On Engine Running)
• Previous dealer repair: PCM replaced, mentioned “Coolant Fan Harness Short Due to Open Diode”
• Code P0480 (Coolant Fan 1 control circuit) identified

What are people suggesting to fix issue

• Check if the low-speed fan works
• Test relay and wiring for the low-speed fan
• Check for a shorted diode in the fan circuit
• Consider recall 05046A related to fan harness wiring for voltage spikes
• Look for possible wire damage or corrosion near the ECM

What was the final fix

• Installed a new harness
• Replaced a 30amp fuse that was assumed to be good previously

Case #2: Saturn

Vehicle Information 2007 Saturn Vue 2.2L with cooling fan issue

Issue + Repair History

• Setting a P0480 – low speed fan control circuit fault
• Initially, no control of low speed with the scan tool, high speed control was fine
• No continuity from relay to fan, found resistor burnt and broken
• Replaced PCM, low speed resistor, and low speed relay
• Problem persisted; fan commanded on by vehicle, then remained on
• Replaced parts: PCM, low-speed resistor, low-speed relay

Other Test Results

• Low speed fan couldn’t be commanded with scan tools
• Continuity test for low-speed fan control circuit was ok, no shorts to power or ground, resistance was .32 ohms

What are people suggesting to fix issue

• Check electrical diagrams and flowcharts for diagnosing P0480
• Measure the amps the motor is pulling and check with a scope
• Test both high and low-speed circuits under load
• Check PCM pin for complete circuit through low fan relay control coil
• Consider that the issue might be on the control side of the relay, not the load side

What was the final fix

• The problem was due to a loose connection at the PCM connector for the fan 1 relay control
• Re-securing the pin in the PCM connector solved the issue

Case #3: Land Rover

Vehicle Information 2008 Land Rover Range Rover HSE 4.4L with A/C and cooling fan issues

Issue + Repair History

• Vehicle was in an accident a year prior
• Compressor inoperative, A/C system evacuated and recharged, but was undercharged (~3/4 lb recovered, recharged to 1.76 lbs)
• A/C compressor has no power, and there’s a P0480 code for low-speed cooling fan relay circuit fault
• Uncertain if the cooling fan circuit problem would prevent the compressor from activating
• Alldata and Identifix had no direct diagnostic routines for this specific issue

Final Fix

• Problem with the low side pressure hose which included a non-replaceable pressure cut-off switch
• The pressure switch prevented the compressor from activating despite correct charge
• Replacing the hose assembly with the switch resolved the issue
• P0480 code set due to the issue with the pressure switch
• Hose assembly was costly (~$900)

Other Test Results

• P0480 code, but no additional information from Alldata
• No A/C operation

Suggestions from Other Technicians

• Russell Boulding: Use a schematic to trace the circuit and check for bad grounds
• Avinash Chandra: Check the power source for A/C compressor and cooling fan, which could be from a 40 AMP fuse and suggest to check Cooling fan and A/C relays separately
• Adam Stanwick: Mentioned that with the P0480 code, the A/C operation would be disabled and usually, this code is caused by a bad fan; pointed out that the engine fan control is directly modulated by the PCM

Learning Points

• A/C system functionality can be linked with other systems such as the cooling fan circuit; issues in one can affect the other
• Using vehicle-specific schematics is crucial for tracing electrical issues
• For complex systems, consult multiple sources and consider the interdependencies of vehicle components
• Even non-obvious components like a pressure switch in a hose assembly can cause systemic issues like disabling the A/C compressor and triggering fault codes
• The cost of parts for luxury vehicles like a Land Rover can be very high, highlighting the importance of accurate diagnostics to avoid unnecessary replacements

Case #4: Volkswagen

Vehicle Information 2006 Volkswagen Jetta Value Edition, 2.5L

Issue + Repair History

• Cooling fans running constantly regardless of ignition position.
• Code P0480 (cooling fan 1 circuit malfunction) present.
• Previous repairs include fan and temperature sensor replacements.

Other OBD2 Codes + Test Results

• No other codes mentioned.

Suggestions to Fix Issue

• Check the commanded state of fans from scan data.
• Convince customer to replace with new fans due to known failure rates.
• Check wiring, particularly the wire from PCM to the fan for issues.
• Consider possible ECM issue if wiring checks out.

Final Fix

• Repaired a corroded wire 10 inches from the PCM inside the wire harness. Fans now operate correctly.

Case #5: Chevrolet

Vehicle Information 2002 Chevrolet Cavalier LS, 2.2L

Issue + Repair History

• SES and traction control light on, Fuse for cooling fan 1 blown.
• Code P0480 (cooling fan relay 1 control circuit) in memory.
• Replacing fuse immediately blew it again; tried a circuit breaker which also kicked out.
• Idle fluctuating and vehicle losing power when AC is on.
• Past service included an oil change, noticing the SES light, replacing the fuse, and advising the customer to monitor the lights.

Other OBD2 Codes + Test Results

• No additional codes mentioned.
• Vehicle experienced high calculated load with minimal pedal application.

Suggestions to Fix Issue

• Check wiring diagrams for short circuits.
• Inspect connector under the battery tray for shorts.
• Suggested lab scope testing of the fan for amp draw and pattern.
• Unplug the fan before installing a new fuse to test for short in fan or power circuit.

Final Fix

• Shorted cooling fan motor was causing the fuse to blow.
• Replaced the cooling fan and a plugged fuel filter, which fixed the idle and power issue.

Advice	Brief Description of Diagnostic Step
Inspect cooling fan and connector	Check for any visual signs of damage, corrosion, or shorting in the fan motor or its connector. Unplug the fan to see if this stops the fuse from blowing.
Test cooling fan motor resistance	Measure the resistance of the cooling fan motor to ensure it is within specifications. A significant deviation may indicate a shorted motor.
Check wiring for shorts	Look for damaged wiring that could cause a short, particularly in areas that are prone to wear, corrosion, or contact with sharp edges.
Examine the related fuse and circuit	Ensure the correct amperage fuse is used and check the circuit for shorts to ground or other faults.
Consider replacing with new parts	Be cautious with used parts, as the failure rate can be high. New parts may offer more reliability.
Review scanner data	Check the commanded state of the fan via scanner data to determine if the PCM is instructing the fan to turn on when it shouldn’t.
Confirm power and ground circuits	Verify the integrity of power and ground circuits to the fan, as issues here can cause the fan to run constantly or not at all.
Evaluate the control module (if separate)	If the vehicle’s fan has a separate control module, assess its function as it can often fail and cause fan operation issues.