Chevy Trailblazer P0480: Definitions, Causes and Diagnosis

OBDII code P0480 is quite common.  It indicates that your Chevy Trailblazer’s “cooling fan 1 control circuit” is malfunctioning.  It’s a generic code, so it has the same meaning for any vehicle made for the 1996 model year and up.

P0480 Definition:  Cooling Fan 1 – Control Circuit Malfunction

Below is P0480 definition for Chevy Trailblazer. It's broken down into its two main parts. 

1. Cooling fan

Electric cooling fans are now standard equipment in modern vehicles.  When your Trailblazer's temperature reaches a specified level, they are automatically activated by the powertrain control module (PCM).  They will turn on either one or both when your air conditioner runs.

Control Circuit Malfunction

If the PCM has commanded cooling fan 1 to turn on, but there is an error, P0480 will be stored in the PCM’s memory.  This occurs if either the fan doesn’t respond or the PCM detects a serious fault in the control circuit.

P0480 Symptoms: Chevy Trailblazer

The Trailblazer's P0480 should drive no different.  The engine's performance will not be affected by the fan (unless the engine is overheated).  The engine might start to knock, misfire, or smoke if you heat it too much.

As stated above, driving your Trailblazer without a functioning fan can cause it to overheat, particularly if you are driving on a hot day or you’re in heavy traffic.  This can cause your air conditioner not to work properly.

You’ll want to keep an eye on the temperature gauge and fix P0480 as soon as possible.  If you overheat, you might blow the head gasket which can lead to more expensive repairs.

Chevy Trailblazer P0480 Causes and Diagnosis

Below are possible causes of P0480.  This code can have many causes.  These are listed in an order that allows you to verify their authenticity.  

1. Look for other codes

You can gain invaluable insight by cross-referencing codes.  You might be able to clear the Trailblazer's P0480 code by repairing a code that is related to the engine temperature sensor.

2. 1. Check out Cooling Fans

Unplug the battery.  You don’t want the fan spinning up (which could happen if you try and spin it and the vehicle is hot).

There are two Chevy Trailblazers that you love, and the one who is most popular will be your Chevy Trailblazer. NOT directly in front of your air conditioner Is almost always fan 1.

You’re going to spin the fan to see if it’s locked up or otherwise bad.  Before spinning the fan, make sure the engine and battery are cold.  When the engine heats up, fans can switch on by themselves.

If the fan requires effort to spin, then it’s bad.  It should be replaced to fix the P0480 problem in Trailblazer.  Try clearing the codes again to check if it is back.

3. Examine the wiring harness at the fan

The fan should be spinning well. If not, make sure to check the wiring harness.  Debris from roads can damage fan wiring.  If you live in an area that is chipmunk friendly, don’t be surprised if they chewed the wiring.  I’ve seen this a few times.

Verify that all terminals have been securely plugged into the fan.  Check that all pins have been checked for corrosion.

4. Examine the Fuses and Fan Relay

Now that we have verified that nothing obvious is causing P0480, it’s time to take a look under your Trailblazer’s hood at the fan relay.  Before you do, inspect the fan relay fuses to make sure that they haven’t been blown.  This can be done visually.  You can verify that the fan relay is powered on.

Now it’s time to take a look at fan relay 1 itself.  Check out the video below, it’ll show you how to test the fan relay with a multimeter.  If there’s no power going to the relay, you’ll need to find where the short is.

5. Others P0480 Reasons

Here are some other common causes of P0480, although they aren’t as common as the ones listed above:

• VSS (vehicle Speed Sensor)
• Refuse to Intake Air Temp Sensor
• A/C Pressure switch

Conclusion

A bad fan, or relay of a fan can often cause P0480.  Good luck fixing your Chevy Trailblazer!