"Fire up a Google Chrome web browser, log into your Tesla account. Click on the "manage" button, wait until it loads your "overview". Right click on the page and then "view page source". Now you can see that page in it's source code format. From here, press Ctrl+F (Find) and search for word "5YJ". If you see something like this "vin":"
5 YJ XXXXX X
K F 418XXX", you have your VIN."
Original post is here
Reveal your VIN before it appears on your account
Or you could add a chrome extension and it will do it for you....
Tesla VIN finder