The E4OD and 4R100 units are programmed from the factory to apply lock-up immediately after the 1 – 2 shift. Many of the units on which Transtar customers work have logged 100,000 miles or more and the vehicles they are in are not generating the power they originally did.

As a result, if the lock-up is applied immediately after the 1 – 2 shift, the vehicle will have difficulty pulling itself through the gear.

The lock-up delay solenoid will set the lock-up timing back just enough to allow the engine to increase its torque output and allow the vehicle to continue adequate acceleration.

The on board computer controlling the lock-up clutch in an E4OD or 4R100 unit issues the command that signals the converter to lock up.

Several seconds later, the computer checks to see that lock-up has occurred.

The time from the signal until the computer checks back is called "the window." (See blue area)