Overdrive Range - Fourth Gear - TCC Applied

Overdrive Range - Fourth Gear (Torque Converter Clutch Applied):

OVERDRIVE RANGE - FOURTH GEAR ([1][2]Torque Converter Clutch Applied)

The [1][2]torque converter clutch applies during fourth gear operation after the Powertrain Control Module (PCM) receives the appropriate input signals to energize the torque converter clutch solenoid (TCC solenoid). To apply the torque converter clutch, the following changes take place in the electrical and hydraulic systems:

Torque Converter Clutch (TCC) Solenoid: When energized (ON), this three port, pulse width modulation (PWM) solenoid operates on a negative duty cycle at a fixed frequency of 32 Hz. The PCM controls the duty cycle (on time versus off time) based on vehicle operating conditions to enable a smooth apply of the [1][2]torque converter clutch. Filtered 3rd clutch fluid acting on one end of the solenoid forces the converter clutch control valve to shift against the opposing force of the spring.

Converter Clutch Control Valve: When shifted by filtered 3rd clutch fluid acting on the end of the valve, filtered 3rd clutch fluid enters the TCC control circuit. However, the pulse width modulation action of the converter clutch solenoid controls filtered 3rd clutch fluid pressure entering the TCC control fluid passage. TCC control fluid pressure is then routed to the converter clutch regulating valve and to the TCC enable valve.

Converter Clutch Regulating Valve: Biased by TCC control fluid pressure, spring force and orificed apply fluid, it regulates line pressure entering the regulated apply circuit. Regulated apply fluid is routed to the converter clutch control valve and through orifice #34 where it enters the orificed apply fluid passage. Orifice apply fluid is then routed to the spring side of the converter clutch regulating valve.

Converter Clutch Control Valve: When the valve is shifted against spring force, regulated apply fluid (from the converter clutch regulating valve) enters the converter apply circuit. Converter apply fluid is then routed to the apply side of the torque converter pressure plate. TCC feed limit fluid, previously feeding into the converter release circuit, passes through the valve and enters the "to cooler" circuit.

TCC Enable Valve: When shifted by TCC control fluid pressure against spring force, it prevents TCC feed limit from entering the orificed TCC exhaust enable passage.


NOTE: After the transaxle is operating with the [1][2]torque converter clutch applied, the cooler and lubrication circuits function in the same manner as previously explained in Reverse gear range. Release fluid is then exhausted through the TCC enable valve.