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

Instrument Panel


Object Number: 1699704  Size: LF
(1)Trailer Park Brake Control (JE4)
(2)Park Brake Control (JE4)
(3)Gage Center
(4)Inflatable Restraint I/P Module (AK5)
(5)Auxiliary Power Outlets
(6)Air Brake Pressure Gage (JE4)
(7)Transfer Case Shift Control Switch (NP1)
(8)Traction Control Switch (NW9)
(9)Outside Heated Mirror Switch (DB6/DB8)
(10)Exhaust Brake Switch (K40)
(11)Rear Axle Driver Control Switch - Two Speed (HPZ/Automatic Transmission)
(12)Inflatable Restraint I/P Module Disable Switch (AK5 w/o AQR)
(13)Differential Lock Switch (HNB/HPL/HPN) or Inter-Axle Differential Lock Switch (Tandem Axle)
(14)Switch
(15)Air Suspension Dump Switch (G40/G45/GSJ)
(16)Diesel Particulate Filter (DPF) (Diesel Only)
(17)Marker Lamp Switch (RQ2 and U86 or RQ3)
(18)High Idle Switch (UF3)/Power Take-Off (PTO) Switch
(19)Air Cleaner Restriction Gage (UPM)
(20)Automatic Transmission Fluid Temperature (TFT) Gage (Allison® LCT/UXT)
(21)I/P Switchbank
(22)HVAC Control Assembly (C40/C60)
(23)Driver Information Center (DIC)
(24)Radio (w/o UL5)
(25)Inflatable Restraint Steering Wheel Module (AJ3/AK5)
(26)Headlamp Switch
(27)Turn Signal/Multifunction Switch
(28)Instrument Panel Cluster (IPC)
Figure 2:

Two Speed Rear Axle Harness, Left Rear View


Object Number: 690061  Size: SF
(1)Rear Axle Shift Relay -- Two Speed
Figure 3:

Rear Differential, Front View


Object Number: 690066  Size: SF
(1)Rear Axle Shift Motor -- Two Speed
Figure 4:

Manual Transmission


Object Number: 953494  Size: LF
(1)Rear Axle Driver Control Switch - Two Speed (HPZ/Manual Transmission) or Two Speed Rear Axle Control Valve (HR2/Manual Transmission)
(2)Backup Lamp Switch
(3)Vehicle Speed Sensor (VSS)