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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 549 (Electric Cooling Fans) >> Diagnostic Tests >> DTC P0495 >> Test Description

Test Description

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the test step numbers.

  1. 2)

    This step ensures that the DTC has failed this ignition cycle. If the scan tool displays Passed, then the answer is No.

  2. 3)

    The cooling fan noise should increase as the cooling fan engages. It can take up to 2 minutes for full cooling fan engagement. If cooling fan is previously fully engaged, then there will not be a noticeable change in cooling fan noise. Compare noise to a known good vehicle. If fan noise is louder than the known good vehicle, then answer Yes.

  3. 4)

    In the previous step the cooling fan was fully engaged. This step tests to ensure that the cooling fan will disengage. A noticeable noise difference should be heard between a fully engaged cooling fan and a disengaged cooling fan. The cooling fan is completely disengaged when the excessive fan noise is not heard.

  4. 5)

    Tests the ability of the PCM to control the cooling fan speed. If answer to question is Yes, see DIAGNOSTIC AIDS  .

  5. 6)

    Disconnecting the cooling fan and running the engine ensure that the cooling fan is not engaged. When rotating the cooling fan it should spin freely. If not then the cooling fan will not disengage.
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