Partial Lock – up

Partial Lock – up

Lock – up Control Solenoid Valve A: ON. Lock – up Control Solenoid Valve B: OFF The transmission control module switches the solenoid valve A on to release the modulator pressure in the left cavity of the lock – up shift valve. The modulator pressure in the right cavity of the lock – up shift valve overcomes the spring force and the lock – up shift valve is moved to the left side.

The modulator pressure is divided into the two passages:

• Torque Converter Inner Pressure: Enters into right side – to engage lock – up clutch
• Torque Converter Back Pressure: Enters into left side – to disengage lock – up clutch

The back pressure (F2) is regulated by the lock – up control valve whereas the position of the lock – up timing valve is determined by the throttle B pressure, tension of the valve spring and pressure regulated by the modulator. Also, the position of the lock – up control valve is determined by the back pressure of the lock – up control valve and torque converter pressure regulated by the check valve. With the lock – up control solenoid valve B off, the modulator pressure is maintained in the left end of the lock – up control valve. With the control valve moved slightly to the left, the back pressure is lowered slightly, resulting in partial lock – up.

Key to hydraulic flow diagram

Note: The components shown in this illustration have the same reference letters as those on the preceding pages.

1. P Lock – up control solenoid valve A
2. Q Lock – up control solenoid valve B
3. V Lock – up shift valve
4. W Lock – up control valve
5. Z Torque converter
6. DD Lock – up timing valve
7. EE Torque converter check valve
8. FF Regulator valve
9. II Oil cooler relief valve
10. JJ Relief valve
11. KK Oil pump
12. MM Oil cooler
13. XX Modulator pressure
14. YY Line pressure