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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1451 (Engine Cooling System) >> Diagnostic Information and Procedures >> DTC P0480: Cooling Fan Relay Control Circuit >> Circuit Description

Circuit Description

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The powertrain control module (PCM) sends a pulse width modulation (PWM) signal of 0-12 volts via the cooling fan clutch control circuit to the cooling fan relay. The PCM monitors the cooling fan clutch control circuit during vehicle operation. When the cooling fan clutch is commanded on by the PCM, the control circuit is at a low voltage. When the cooling fan clutch is commanded off, the control circuit is near battery voltage. The PCM uses this PWM to control the position of the oil control valve located inside the cooling fan clutch. If during operation, the PCM detects an improper circuit condition on the cooling fan clutch control circuit DTC P0480 will set.