GM Service Manual Online
For 1990-2009 cars only

Auxiliary Cooling Fan Circuit Description

Power is supplied at all times to the Auxiliary Cooling Fan Relay from the AUX FAN Fuse in the Underhood Fuse Block through CKT 1540 (ORN). CKT 1240 (ORN) supplies voltage to the Auxiliary Cooling Fan Relay coil from the A/C COMP Fuse. The Auxiliary Cooling Fan Relay is energized when the Vehicle Control Module (VCM) grounds CKT 473 (DK BLU), energizing the coil. When the Auxiliary Cooling Fan Relay energizes, internal contacts close allowing voltage from the AUX FAN Fuse supplying voltage to CKT 702 (RED) which feeds the Auxiliary Cooling Fan Motor. The Auxiliary Cooling Fan Motor is grounded through CKT 250 (BLK) to ground G112.