Transmission Control Systems: Description and Operation

Fig. 1 KM171 Automatic Transaxle. (KM172, F3A21 & F3A22 Similar):

The F3A21 transaxle is a hydraulically operated automatic three speed transaxles with an electronically controlled lock-up torque converter. This transaxle is used on all Colt and Eagle Summit models with 1.5L/4-96 engines.

The Electronic Control Module receives inputs from the following:

- Pulse Generator "A"
- Pulse Generator "B"
- Coolant Temperature Sensor
- Throttle Position Sensor
- Idle Motor Position Switch

The Electronic Control Module calculates if a change in torque converter operation is needed and controls the following output:

- Damper Clutch Control Solenoid Valve