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

Air Suspension Dump Valve


Object Number: 397225  Size: LF
(1)Air Suspension Dump Valve
Figure 2:

Center and the Right I/P


Object Number: 1430017  Size: LF
(1)Marker Lamp Switch (RQ2 and U86 or RQ2)
(2)High Idle Switch (UF3)
(3)Traction Control Switch (NW9)
(4)Outside Heated Mirror Switch (DB6/DB8)
(5)Exhaust Brake Switch (K40)
(6)Rear Axle Driver Control Switch - Two Speed (HPZ/Automatic Transmission)
(7)Air Suspension Dump Switch (G40/G45/GSJ)
(8)Power Take-Off (PTO) Switch
(9)Driver Information Center (DIC)