GM Service Manual Online
For 1990-2009 cars only

Power Distribution

Power supply for the vehicle originates from the battery(s). From the battery(s), voltage is supplied to the Generator, Starter Motor Solenoid, Mega Fuse Block (Luxury/Police Package), Underhood Fuse Block and Auxiliary Fuse Block (Police Package) through CKT 2 (RED).

The Underhood Fuse Block supplies power to various components within the vehicle. From the Underhood Fuse Block, power is sent to the IP Fuse Block through either CKT 42, 142, or 242 (RED). The Underhood Fuse Block along with the IP Fuse Block distribute power to all the major and minor electrical systems within the vehicle. See the Power Distribution Schematics for other components.

Ground Distribution

Circuitry for grounding is used to complete the path for current flow. Grounding circuits are primarily 150 or 451 circuit numbers. See Ground Distribution Schematics for component grounding breakdown.

Auxiliary Battery

The auxiliary battery circuit uses a relay to complete the connection between the Auxiliary Battery and the Remote Battery Stud located on the Underhood Fuse Block.

Power to activate the Auxiliary Battery Relay comes from the 4WD Fuse 24, through CKT 241 (BRN) when the ignition switch is in the RUN position. The relay is case grounded to complete the path for current flow. With the relay activated, power from the Auxiliary Battery runs through CKT 2 (BLK/RED) onto the Remote Battery Stud.