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

Ignition and Accessory Voltage


Object Number: 1843654  Size: FS
Master Electrical Component List
Power Mode Description and Operation
Control Module References
Ignition 2 and 3 Voltage
B+ Bus - 1 of 3
G102 and G108
G102 and G108
Figure 2:

Ignition 1 Voltage


Object Number: 1843656  Size: FS
Master Electrical Component List
Power Mode Description and Operation
Control Module References
Ignition 2 and 3 Voltage