GM Service Manual Online
For 1990-2009 cars only
Figure 1:

Power, Ground, and Serial Data


Object Number: 848144  Size: FS
Master Electrical Component List
Instrument Cluster Description and Operation
Gages
B+ Bus - Underhood Fuse Block
IGN B Fuse
SPARE, IGN E, SIR, TBC IGN 1, and ISRV Fuses
SPARE, IGN E, SIR, TBC IGN 1, and ISRV Fuses
G302
G303, and G304
Data Link Schematics
Figure 2:

Gages


Object Number: 848145  Size: FS
Master Electrical Component List
Instrument Cluster Description and Operation
Indicators
Power, Ground, and Serial Data
Data Link Schematics
5 Volt Reference (4.3L)
5 Volt Reference (4.8L, 5.3L, and 6.0L)
Figure 3:

Indicators


Object Number: 887457  Size: FS
Master Electrical Component List
Instrument Cluster Description and Operation
Gages
Turn Signal/Hazard FLasher Module, and DR TRN MIR, PASS TRN MIR Fuses
Data Link Schematics
G103, G104, G105, G106, G300, and G301
Brake Warning Schematic