Lumina V6-3.8L VIN K (1998)
Torque Converter Clutch Solenoid: Description and Operation
4T60-E Automatic Transaxle
TCC CONTROLS
Most Hydra-matic 4T60-E transaxle models also use two solenoid valves to control TCC apply and release. The first solenoid valve in this system is
the pressure controlling solenoid. It is a Pulse Width Modulation (PWM) solenoid valve that acts as a direct bias on the converter clutch regulator
valve. This solenoid valve is normally open.
The other solenoid valve is an ON/OFF solenoid valve with a 2-port design that is identical to the two shift solenoid valves. This type of system
provides for accurate control of regulated apply pressure that feeds the apply side of the torque converter clutch plate.
TORQUE CONVERTER CLUTCH PULSE WIDTH MODULATION SOLENOID VALVE
The PCM controls the Torque Converter Clutch Pulse Width Modulation Solenoid valve (TCC PWM Sol valve) by varying its operating duty cycle
(ON/OFF time) from 0% to 100%. Until the transmission is operating in 3rd gear, the TCC PWM Sol valve is OFF. In this state, filtered PWM feed
pressure flows at maximum pressure through the solenoid and into the PWM circuit.
When the TCC PWM Sol valve is energized, the valve operates at 32 Hz (cycles per second) and from 0% to 100% duty cycle depending on vehicle
operation. The TCC PWM Sol valve is enabled to modulate the amount of PWM feed pressure passing through the solenoid, sending it to the
converter clutch regulator valve. At 0% duty cycle, the torque converter clutch applies at maximum capacity. At 100% duty cycle the clutch applies at
minimum capacity.
TORQUE CONVERTER CLUTCH SOLENOID VALVE
The Torque Converter Clutch Solenoid valve (TCC Sol valve) is an ON/OFF solenoid that functions in the same manner as the 1-2 shift solenoid
valve and the 2-3 shift solenoid valve. As with the shift solenoids, the PCM provides the ground to command the TCC Sol. valve ON or OFF. The
only difference in operation is that ignition voltage is supplied through the normally closed brake switch to the solenoid. When the solenoid is OFF,
and if the transmission is operating in third or fourth gear, the TCC signal fluid exhausts through the solenoid. When energized (ON), the exhaust port
is blocked. This allows the TCC signal fluid pressure to move the converter clutch valve against the spring force and the line pressure at the opposite
end of the valve.
