Control Module: Description and Operation

The EC-AT (Electronically Controlled Automatic Transmission) Control Unit, located under the dash left of the steering column, is the control unit for various electrically operated functions of the F4A-EL automatic transaxle. One of these functions is torque converter lockup or lockup inhibit, activated according to operating conditions. Control of ATF flow to the torque converter and lockup are achieved by EC-AT control unit energizing and de-energizing the transmission lockup solenoid. The ATF passage is closed when current is applied and open when current is cut.

To coordinate engine operating conditions with transmission functioning, the ECU sends a signal to the EC-AT control unit (an output from the ECU). The signal informs the control unit of engine coolant temperature, an input used to calculate lockup control. Lockup is permitted during most driving conditions but specifically inhibited when the control unit receives a coolant temperature signal below 72°C (162°F).