You won't know it needs replacing - it fails catastrophically, without any symptoms. Factory recommended replacement mileage is 95,000 miles. If you have passed that mileage you are living on borrowed time.
Timing belt and water pump $500.00 - 600.00.
You don't as it has a chain not a belt.
Factory recommendation is 90,000 miles.
Factory recommended at 90,000 miles.
It has a belt. Replace it every 90,000 miles.
The 3.3 liter V6 in a 2007 Toyota Highlander has a timing BELT
I have a 2006 Toyota highlander hybrid, do I need to change timing belt or chain?
The manual states at 90,000 miles.Factory recommends 90,000 miles.
Toyota recommends replacing the belt every 90,000 miles.
In 2008 the Toyota Highlander V-6 engine was equipped with a timing CHAIN.
Timing belt
Go to 'you tube'. There are several videos showing step by step instructions on there.