Tools and materials:
* Wrench set
* Screwdriver
*Hydraulic transformer puller (optional)
* New transmission filter
* New gear oil
Steps:
1. Prepare the car
* Park the car on a level surface.
* Put the car on the parking brake.
* Allow the engine to cool.
2. Disconnect the battery
* Disconnect the negative battery cable to prevent short circuit.
3. Drain transmission oil
* Locate the transmission drain plug and place a suitable container under it.
* Unscrew the drain plug and drain the oil.
* Tighten the drain plug when all the oil has been drained.
4. Remove the subframe
* Remove the bolts securing the subframe to the car body.
* Carefully lower the subframe using a jack or supports.
5. Disconnect the transmission hose
* Locate the transmission hose and disconnect it from the transmission.
* Plug the end of the hose to prevent oil leakage.
6. Disconnect electrical wiring
* Disconnect all electrical connectors from the transmission.
7. Disconnect wheel drives
* Unscrew the nuts securing the wheel drives to the hubs.
* Remove the wheel drives from the gearbox.
8. Unscrew the gearbox mounting bolts
*Locate the bolts holding the transmission to the engine.
* Remove all bolts.
9. Disconnect the torque converter
*If the transmission is equipped with a hydraulic transformer, use a puller to remove it from the flywheel.
10. Remove the gearbox
* Carefully remove the transmission from the vehicle using a jack or lift.
* Reinstall the new gearbox by following the steps in reverse order.
11. Replace the transmission filter
*Remove the old transmission filter.
* Install a new filter.
12. Fill with transmission oil
* Pour new gear oil into the gearbox through the filler plug.
* Install the filler plug.
13. Connect the battery
* Connect the negative battery cable.
14. Bleed the gearbox
* Start the engine and let it idle.
* Shift the gear selector through all positions several times.
* Check the transmission oil level and add oil if necessary.
15. Testing
* Drive the vehicle to ensure that the transmission is operating properly.
Note: These instructions are general and may vary depending on your specific Toyota Avensis model. It is recommended that you consult your repair manual for specific instructions.