Engine Controls

WARNING: This page does not describe the selected car, but rather 17 other vehicles, including the 2004 Toyota Tundra, 2004 Toyota Tacoma, 2004 Toyota Sienna, 2004 Toyota Sequoia, and 2004 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.

Vehicles equipped with powertrain control computers may require a computer relearn procedure after the vehicle battery is disconnected. Vehicle computers memorize and store vehicle operation patterns for optimum driveability and performance. When the vehicle battery is disconnected, this memory is lost, which may result in a driveability problem. Depending on the vehicle and how it is equipped, the following driveability problems may exist:

Rough or unstable idle.
Hesitation or stumble.
Rich or lean running.
Poor fuel mileage.
Harsh or poor transmission/transaxle shift quality.

Default data is used until NEW data from each key start is stored. As the computer restores its memory from each new key start, driveability is restored.

Driveability problems may occur during the computer relearn stage. To accelerate computer relearn process after battery removal and installation, specified computer relearn procedures should be performed. See appropriate procedure for specific model.