The windshield washer pump is located in front of the passenger front tire behind the fender cover. I had the same problem and found out that it has one pump for both windshields (two discharge outlets). The front worked perfect. I blew air through the rear window hose and it was clear. I went to the local auto store and found that they only sold a pump with one discharge outlet. I went to Toyota and told them to give me a pump for a Highlander. It was exactly the same as my Lexus. After the installation, the windshield washers work great. I don't know why the front worked and the rear didn't but, $70 later and now it works.