Description & Operation
The 4F27E is a fully automatic, electronically controlled 4-speed transaxle. Individual gear ratios are achieved through 2 planetary gear sets connected one behind the other. Individual components of the planetary gear sets are driven or locked by 3 multi-plate clutches, a multi-plate brake, a brake band and a roller one-way clutch. Torque is transmitted to the final drive assembly through an intermediate gear stage.
Electrical and hydraulic functions are controlled by a 104-pin EEC-V Powertrain Control Module (PCM). The torque converter lock-up clutch is engaged by the PCM in 3rd and 4th gears depending on throttle position and vehicle speed to reduce fuel consumption. The transaxle has Electronic Synchronous Shift Control (ESSC) to guarantee smooth gear shifting. A hydraulic emergency operating program allows limited operation of transaxle in the event of failure of important electrical components. The transaxle can be tested using FDS2000, WDS or equivalent scan tool connected to Data Link Connector (DLC), located under left side of instrument panel.
The valve body contains 6 solenoid valves. The main regulating valve, or Pressure Control (PCA) solenoid, controls the required main line oil pressure for individual transaxle ranges dependent on the current engine load. The 2 shift solenoids switch different oil passages in the valve body to direct the oil pressure to the individual brakes and clutches. The 3 Pulse Width Modulation (PWM) valves control the amount of oil pressure to the brakes and clutches.