The solenoids in the 4F27E automatic transmission perform the following functions:
Linear solenoids:
* EPC (Line Pressure) Solenoid: Regulates the main line pressure line pressure that supplies all clutches and brake bands.
* TCC (Transmission Torque Converter) Solenoid: Engages and disengages the torque converter clutch.
Regulating solenoids:
* PC (Proportional Control) Solenoid: Regulates the line pressure to the 2-4 clutch.
* TC (overrunning clutch) solenoid: Controls the overrunning clutch in drum 3-4, allowing it to turn freely under certain conditions.
Shift solenoids:
* Shift Solenoid 1-2: Shifts the transmission between 1st and 2nd gears.
* Shift Solenoid 2-3: Shifts the transmission between 2nd and 3rd gears.
* 3-4 Shift Solenoid: Shifts the transmission between 3rd and 4th gears.
Torque converter lock-up solenoid:
*Transformer Lockup (TL) Solenoid: Controls torque converter lockup, which helps reduce slippage and improve fuel economy at higher speeds.