P0480 Cooling Fan Relay 1 Control Circuit

Trouble Code P0480 OBD-II Datasheet

Cooling Fan Relay 1 Control Circuit

What does code P0480 mean?

This is a Generic Transmission Diagnostic Trouble Code (DTC), which means it applies to all makes / models from 1996 onwards. However, specific troubleshooting steps may differ from vehicle to vehicle.

If your vehicle's check engine light comes on and after you pull out the code, you will find that P0480 is displayed if it relates to the engine cooling fan circuit. This is a generic code applied to all vehicles with OBD II on-board diagnostics.

When driving, a sufficient amount of air flows through the radiator to effectively cool the engine. When you stop the car, air does not pass through the radiator and the engine starts to heat up.

The PCM (Powertrain Control Module) detects an increase in engine temperature through the CTS (Coolant Temperature Sensor) located next to the thermostat. When the temperature reaches approximately 223 degrees Fahrenheit (the value depends on the make / model / engine), the PCM commands the cooling fan relay to turn on the fan. This is achieved by grounding the relay.

An issue has occurred in this circuit that causes the fan to stop working, which causes the motor to overheat when you sit still or drive at low speed. When the PCM tries to activate the fan and detects that the command does not match, the code is set.

NOTE: P0480 refers to the main circuit, however codes P0481 and P0482 refer to the same problem with the only difference that they refer to different fan speed relays.

Symptoms of a P0480 trouble code may include:

Symptoms may include:

• Check engine light (malfunction indicator lamp) and set code P0480.
• The engine temperature rises when the vehicle is stopped and idling.

Possible reasons

Reasons for this DTC may include:

• Faulty fan control relay 1
• Open or short circuit in the fan control relay harness
• Poor electrical connection in the circuit
• Defective cooling fan 1
• Defective coolant temperature sensor
• Cooling fan harness open or shorted
• Bad electrical connection in the cooling fan circuit
• Intake Air Temperature (IAT) Malfunction
• Air conditioner selector switch
• Air Conditioner Refrigerant Pressure Sensor
• Vehicle speed sensor (VSS)

P0480 Diagnostic and Repair Procedures

It is always a good idea to look at the technical service bulletins (TSBs) for your specific vehicle to find out what complaints have been filed with the dealer's service department related to this code. Search with your favorite search engine for "service bulletins for ... .." Find the manufacturer's recommended repair code and type. It's also a good idea before buying a car.

Many vehicles will have two engine fans, one to cool the engine and one to cool the A/C condenser and provide additional engine cooling.

The fan that is not in front of the air conditioner condenser is the main cooling fan and should be the focus initially. In addition, many vehicles are equipped with multi-speed fans, which require up to three fan speed relays: low, medium, and high.

Open the hood and carry out a visual inspection. Look at the fan and make sure there are no obstructions in front of the radiator blocking air flow. Spin the fan with your finger (make sure the car and the key are turned off). If it does not rotate, the fan bearings will burst and the fan is defective.

Check the electrical connection of the fan. Disconnect the connector and look for corrosion or bent pins. Repair if necessary and apply dielectric grease to terminals.

Open the fuse box and inspect the cooling fan relay fuses. If they are ok, pull out the cooling fan relay. The bottom of the fuse box cover usually indicates the location, but if not, refer to the owner's manual.

The function of the vehicle's PCM is to act as a ground for component operation, not power supply. The fan relay is nothing more than a remote light switch. The fan, like other devices, draws too much current to be safe in the cab, so it's under the hood.

A permanent battery power supply is present at the terminals of each of the relays. This one turns on the fan when the circuit is closed. The switched terminal will only be hot when the key is on. The negative terminal on this circuit is the one used when the PCM wants to activate a relay by grounding it.

Look at the wiring diagram on the side of the relay. Look for a simple open and closed loop. Check the positive terminal of the battery in the permanently supplied relay box. The opposite side goes to the fan. Use the test light to find the hot terminal.

Connect the battery terminal to the fan harness terminal and the fan will run. If not, disconnect the fan connection on the fan and use an ohmmeter to check for continuity between the fan side relay terminal and the connector on the fan. If there is a circuit, the fan is defective. Otherwise, the harness between the fuse box and the fan is faulty.

If the fan was running, check the relay. Look at the side of the relay at the switchable power terminal or simply turn on the key. Check the terminals for the presence of the auxiliary power terminal and see where it will be on the relay.

Connect the positive terminal of the battery in the first test with this switchable terminal and place an additional jumper wire between the negative terminal of the relay to ground. The switch will click. Use an ohmmeter to test the constant terminal of the battery and the fan harness terminal for continuity, indicating that the circuit is closed.

If the circuit fails or the relay fails, the relay is faulty. Check all relays in the same way to make sure they are all working.

If there was no switched power on the relay, an ignition switch is suspected.

If they are good, test the CTS with an ohmmeter. Remove the connector. Allow the engine to cool and set the ohmmeter to 200,000. Check sensor terminals.

The reading will be about 2.5. Consult your service manual for an accurate reading. Accuracy is not required as all sensors can be different. You just want to know if it works. Plug it in and warm up the engine.

Stop the engine and remove the CTS plug again. Check with an ohmmeter, there should be a large change in resistance, if the sensor is not faulty.

If the above procedure fails to find a fault, it is likely that there is a bad connection to the PCM or the PCM itself is faulty. Don't go further without consulting your service manual. Disabling the PCM may result in loss of programming and the vehicle may not start unless towed to your dealer for reprogramming.

HOW DOES A MECHANIC DIAGNOSTIC CODE P0480?

• Use a scanner and check for codes stored in the ECU.
• Detection of freeze frame data showing coolant temperature, RPM, vehicle speed, etc. from the moment the code is set
• Clear all codes
• Take the car for a test drive and try to reproduce the conditions from the freeze frame data.
• Performs a visual inspection of the ventilation system, closely monitors fan operation, and looks for damaged or worn wiring.
• Use a scan tool to check the data stream and verify that the VSS sensor is reading correctly and that the coolant temperature sensor is reading accurately.
• Use a relay tester to test the fan control relay, or switch a relay with a good relay to test.
• Verifies that the AC pressure switch is operating correctly and is reading within specifications.

COMMON ERRORS WHEN DIAGNOSING CODE P0480

Errors occur when step-by-step diagnostics are not performed or steps are skipped altogether. There are many systems that could be responsible for a P0480 code, and if neglected, the fan could be replaced when it was indeed the coolant temperature sensor that was causing the fans to fail.

HOW SERIOUS CODE P0480 IS?

P0480 can become serious if the vehicle is run hot. Overheating the vehicle can cause engine damage or total engine damage.

If code P0480 is detected and the fans fail, the vehicle cannot be driven.

WHAT REPAIRS CAN FIX CODE P0480?

• Replacing the VSS sensor
• Engine Coolant Temperature Sensor Replacement
• Repair or replace fan harness
• Replacing the cooling fan 1
• Troubleshooting Electrical Connections
• Replacing the air conditioner pressure switch
• Replacing the Fan Control Relay

ADDITIONAL COMMENTS TO BE AWARE OF CODE P0480

Access to the vehicle's real-time data stream is required to diagnose P0480. This is done with a professional scanner. Tools of this type provide much more access to information than scanning tools that simply read and erase codes.

P0480 ✅ SYMPTOMS AND CORRECT SOLUTION ✅ - OBD2 Fault Code

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