Assuming you would like tips on how to properly use your Highlander's All-Wheel Drive:
There are three main ways to engage your Highlander's all wheel drive. The first is by pressing the VSC button (Vehicle Stability Control) which is located on the lower left side of the dash. The second way is by engaging the AWD lock button, which is also located on the lower left side of the dash. The last way is by putting your vehicle in 4WD Low range.
To ensure that your all wheel drive system is working properly, it is important to check the fluid level and condition regularly. You can do this by checking the dipstick that's located near where you fill up your engine oil. If you notice that the fluid level is low or if it looks dirty, be sure to have it checked by a professional as soon as possible as this could be indicative of a larger problem.