This DIY is on a Corolla with a 1zz motor , This belt tensioner has 350,000 miles on it and the only reason this one is being replaced is cause its been on to long not because of failure . I had to rent the belt tensoiner tool because the bolt to take out the belt tensioner leaves you no room for a ratchet and to tight for a open end wrench .
First thing I did was use a open end wrench to loosen the belt tensioner to remove the belt .
Then with my belt tensioner tool I removed the bolt that holds it to the block , At first I loosened it up before removing completely.
Then I removed the mini shock bolt then I went to unscrew the main bolt to the tensioner . It is very tight in there so be careful for the A/C line to not disturb it , Then you slide out the tensioner from the bottom .
Once removed then you put it back together in the same steps
Here is a diagram on how your belt runs .
More DIY at www.corollacarclub.proboards.com