Here's how to turn on 4x4 in a 2009 Toyota Highlander:
1. Make sure you're in a safe location and that it is necessary to engage 4x4. Driving in 4x4 when it's not needed can damage your vehicle.
2. Press the "4WD" button on your dashboard. The 4WD button is typically located near the center of the dashboard, but it may be in a different location in your particular vehicle. If the button is illuminated, it means that the four-wheel drive system is engaged.
3. Shift your transmission into 4L. 4L is the lowest gear in the four-wheel drive system, and it is used for off-road driving or other situations where you need extra traction.
4. Release the "4WD" button to engage 4H. 4H is the highest gear in the four-wheel drive system, and it is used for driving in snowy or slippery conditions.
