Computers and Control Systems: Description and Operation

PURPOSE
The computer control system monitors vehicle speed and throttle opening to maintain proper gear selection for all driving conditions.

OPERATION
When overdrive range is selected, transmission gear selection and converter clutch operation are controlled by the Powertrain Control Module (PCM). Operating conditions are sent to the PCM by various input sensors. The PCM compares the sensor values with internal tables to determine the operating state of the transmission.

The Transmission Control Switch (TCS) disables overdrive operation and allows automatic shifting through the first three gears. Operation of the TCS ceases when the ignition is turned off, allowing the transmission to shift into overdrive when the vehicle is restarted.


COMPONENTS
The computer control system consists of:
- PCM
- Programmable Speedometer/Odometer Module (PSOM)
- Vehicle Speed Sensor (VSS)
- Brake On/Off Switch (BOO)
- RPM sensor
- Air Conditioning Clutch (ACC)
- Barometric Pressure (BARO) sensor
- Low range 4x4 switch
- Throttle Position (TP) sensor
- Transmission Operating Temperature (TOT) sensor
- Manual Lever Position (MLP) sensor
- Transmission Control Switch (TCS)
- Transmission Control Indicator Lamp (TCIL)
- Transmission solenoid body
- Electronic Pressure Control (EPC) solenoid