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

Transmission Control Module (M74)


Object Number: 769662  Size: MF
(1)Transmission Control Module Connectors
(2)Transmission Control Module
(3)Powertrain Control Module (PCM) (Gas) / Engine Control Module (ECM) (Diesel)
Figure 2:

Engine Harness to Transmission-Allison


Object Number: 769664  Size: MF
(1)Turbine Sensor Harness Connector
(2)Power Take-Off (PTO) Connector
(3)Output Speed Sensor Harness Connector
(4)Transfer Case Selector Shift Control Switch
(5)Transmission Connector Harness
(6)Park/Neutral Position (PNP) Switch Connectors
(7)Allison Transmission
(8)Engine Harness
(9)Automatic Transmission Input Shaft Speed (ISS) Sensor
Figure 1:

Automatic Electronic Transmission Harness (LG5/MWF), Upper Right Side Rear


Object Number: 231744  Size: LF
(1)Engine Speed Sensor
(2)Vehicle Speed Sensor (VSS)
Figure 2:

Instrument Panel Switches, Center Forward View


Object Number: 1400889  Size: LF
(1)Outside Heated Mirror Switch (DNN)
(2)High Idle Switch (UF3) or Power Take-Off (PTO) Switch
(3)Exhaust Brake Switch (K40)
(4)Rear Axle Driver Control Switch - Two Speed (HPZ and Automatic Transmission)
(5)Traction Control Switch (NW9)
(6)Overdrive (OD) Defeat Switch (Allison® LCT)
(7)Marker Lamp Switch (JE4, RQ2 and U86, or JE4 and RQ3)
Figure 3:

Transmission Shift Control


Object Number: 397116  Size: LF
(1)Transmission Shift Control
Figure 4:

Front Chassis Harness To Transmission (MTW/MX4)


Object Number: 628965  Size: LF
(1)Front Chassis Harness
(2)Automatic Transmission-MTW/MX4
(3)Automatic Transmission Connector
Figure 5:

Front Chassis Harness To Transmission Control Module (MTW/MX4)


Object Number: 628966  Size: LF
(1)Frame Rail-Left Side
(2)Transmission Control Module (TCM)
(3)Transmission Control Module Connector-C1
(4)Transmission Control Module Connector-C2
(5)Front Chassis Harness