Automatic Transmission Diagnosis - Aw0E-72LE & Aw03-73LE: Description

Automatic transmission is electronically controlled. Transmission shifting and torque converter lock-up are controlled by Powertrain Control Module (PCM).

PCM receives information from various input devices and uses this information to control shift solenoids No. 1 and 2, for transmission shifting, and Torque Converter Clutch (TCC) solenoid for torque converter lock-up. Solenoids are located on transmission valve body.

An Overdrive (OD) switch is mounted on shift lever. When OD switch is depressed to ON position with shift lever in "D" range, transmission will upshift into 4th gear and OD/OFF indicator on instrument panel will go off. When OD switch is released to OFF position, transmission will downshift into 3rd gear, and OD/OFF indicator will illuminate.

A Power/Normal (P/N) switch is located on shift console. Pressing P/N switch toggles between Power and Normal shift patterns. Selecting Normal mode signals PCM to use standard shift pattern and POWER indicator will go off. In Power mode, PCM delays upshifts, initiates downshifts at lower vehicle speeds and illuminates POWER indicator.