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

Horns


Object Number: 354766  Size: LF
(1)Fender, LF
(2)Horn, LH
(3)Insulator
(4)Horn, RH
(5)Fender, RF
Figure 2:

HORN Relay


Object Number: 357898  Size: LF
Figure 3:

SRS Steering Wheel Inflator Module


Object Number: 357153  Size: MF
(1)Multifunction Switch
(2)Horn Switch
(3)Supplemental Restraint System Steering Wheel Inflator Module