TORQUE CONVERTER CLUTCH (TCC) CONTROL DESCRIPTION [JA5A-EL]

Outline

Features

• The TCM selects the TCC schedule according to the gear selected by the transaxle. 50 Hz (20 ms cycle) on/off signals are relayed from the TCC schedule and speed sensor and throttle opening angle to the duty cycle TCC solenoid valve to control TCC.

Construction (system diagram)

Operation

Torque converter clutch (TCC) release operation

• The TCM sends an OFF signal to TCC solenoid valve to release the TCC. In this condition, the TCC control valve is pushed to the up side by spring force and line pressure, and torque converter pressure acts on the torque converter front chamber, releasing the TCC from the converter cover.

Torque converter clutch (TCC) engaging operation

• The TCM determines smooth TCC operation. It sends an ON signal to the TCC solenoid valve to push the TCC control valve to the down side. Consequently, the hydraulic pressure applied to the torque converter front chamber is drained through the TCC control valve, engaging torque converter clutch.

Coast TCC

• Even when the accelerator pedal is released in the TCC range at high speeds, the TCC remains engaged to prevent repetition of TCC engagement/release by depressing/releasing the accelerator pedal, as well as reducing shock during the operation.

Determination of Torque Converter Clutch (TCC) Cancellation

The TCC control is canceled when any of the following condition are met:

• Engine coolant temperature is low.

• ATF temperature is low.

• Brake switch is on (when depressing the brake pedal).

• Accelerator depressing speed and accelerator opening angle are above the set value.

• Engine speed signal is below the set value.

• Failure is in the TCC control system detected by diagnosis function.