This is the tool you need. Plug her in and it tells you everything. Even tells you the part no.s that are require to fix problem. I saw it in action today. Pity it wasn't a bit cheaper or it would be a good investment for a car club.
http://buy.snapon.com/products/diagnostics/mt2599a.asp
http://buy.snapon.com/products/diagnostics/mt2599a.asp