Control of LockUp

The ECT ECU has lock-up clutch operation pattern for each driving mode (Normal and Power) programmed in its memory. The ECU turns the No. 3 solenoid valve on or off according to vehicle speed and throttle opening signals. The lock-up control valve changes the fluid passages for the converter pressure acting on the torque converter piston to engage or disengage the lock-up clutch.

In order to turn on solenoid valve No. 3 to operate the lock-up system, the following three conditions must exist simultaneously:

• The vehicle is traveling in second, third, or overdrive ("D" range).

• Vehicle speed is at or above the specified speed and the throttle opening is at or above the specified value.

• The ECU has received no mandatory lock-up system cancellation signal.

The ECU controls lock-up timing in order to reduce shift shock. If the transmission up-shifts or down-shifts while the lock-up is in operation, the ECU deactivates the lock-up clutch.

The ECU will cancel lock-up if any of the following conditions occur:

• The stop light switch comes on.

• The coolant temperature is below 122'F to 145'F depending on the model. Consult the vehicle repair manual or the ECT Diagnostic Information Technician Reference Card.

• The IDL contact points of the throttle position sensor close.

• The vehicle speed drops about 6 mph or more below the set speed while the cruise control system is operating.

The stop light switch and IDL contacts are monitored in order to prevent the engine from stalling in the event that the rear wheels lock up during braking. Coolant temperature is monitored to enhance drivability and transmission warm-up. The cruise control monitoring allows the engine to run at higher rpm and gain torque multiplication through the torque converter.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

Get My Free Ebook


Responses

  • Wilimar
    How to temporarily disconnect lock up on converter toyota supra?
    3 years ago

Post a comment