GMC 2004 Sierra - Manual (Page 529)

Device Usage
SEO Special Equipment Option
TRAILER Trailer Brake Wiring
UPFIT Upfitter (Not Used)
SL RIDE
Ride Control Harness
Connection
HDLR 2 Headliner Wiring Connector
BODY Body Wiring Connector
DEFOG Rear Defogger Relay
HDLNR 1 Headliner Wiring Connector 1
SPARE RELAY Not Used
CB SEAT
Driver and Passenger Seat
Module Circuit Breaker
CB RT DOOR
Right Power Windows Circuit
Breaker
SPARE Not Used
INFO
Infotainment Harness
Connection
Underhood Fuse Block
The underhood fuse block in the engine compartment
on the driver’s side of the vehicle near the battery.
Lift the cover for access to the fuse/relay block.
To remove fuses hold the end of the fuse between your
thumb and index finger and pull straight out.
See Engine Compartment Overview on page 5-12 for
more information on its location.
5-129