Car wont start

Batteries typically only last 3 years, if your battery has not been replaced in its lifetime that is almost certainly the issue. If you take your vehicle to an auto parts store they will test your battery for you for free.

I have a 2006 toyota sienna the old alternator was replaced with new one it worked and started but they said to replace it i did now it omly cranks wont start whats the problem now

Check that you got all the wiring harnesses around the engine air breather box connected correctly. I go into great detail on how to connect them in this tutorial: http://www.shareyourrepair.com/2014/12/how-to-replace-starter-on-2004-2007-toyota- sienna.html

GuruW6y69 I changed out my alternator and having the same problem. Changed crank sensor, and cam sensors then took it to the shop they said computer was coming up on there test. Removed and sent off come back ( tester said computer was good had no problems) , but still having same problem. Toyota shop said changing the alternative would not cause that, and security system would do that. Still trying to figure it out.

It is an 07 toyota sienna