Automatic Transmission/Transaxle: Description and Operation

Circuit Description
The 097 four-speed automatic transmission is electronically controlled. The automatic transmission control unit operates electromechanical solenoid valves in the transmission valve body to control shift points and other functions. Power to the automatic transmission control unit is supplied directly from the fuse/relay panel (15 circuit) via fuse #12 (S12) whenever the ignition is switched on.

Control of shift points and other functions varies in response to input signals from these components:
- Multifunction switch (gear selector lever position)
- Economy/sport selector button
- Engine electronics (rpm)
- Speed sender
- Throttle valve potentiometer (engine load signal)
- Automatic transmission fluid temperature sensor
- Kickdown switch
- Brake light switch

The automatic transmission control unit controls shift points and other functions with output or actuating signals to the following output components:
- Solenoid valves in transmission valve body
- Shift lock control
- Cruise control

In the Park or Neutral position, the shift lock system locks the gear selector lever until the driver steps on the brake.

The shift lock is activated about 0.2 seconds after the engine is started, or approximately one second after Park or Neutral are selected. The one second delay allows the driver to quickly shift between Drive and Reverse when necessary.

A speedometer input to the shift lock control unit prevents engagement of the shift lock at speeds above 3 mph.