Can appreciate that, wife and I gave her son a nice new HP notebook for his graduation in Venezuela, crapped out, HP in Venezuela wouldn't touch it. He had to ship it back to us, will cost over 300 bucks just in shipping, but free here.
Not easy even for us to get information on brand new stuff, no market for it when it's under warranty.
Helms at http://www.helminc.com
sells manuals, this is what they have to say about your Acadia:
2008 Buick Enclave GMC Acadia Saturn Outlook Service Manual Set
Price: $150.00 Out of Stock.
Click here if you would like to be notified when this item becomes available.
Pkg Qty: 1
(English, Paper, GMT08RV)
Perhaps knowing the engine and transmission type would help, but normally do not have problems finding the ECT sensor, the way they are writing these manuals today, easier to find it in the vehicle than the book.
If somebody pulled the plug off of it, would be infinite resistance emulating an ice cold condition, if this is your problem, you are looking for a short.
Sure helps to have a scanner with these darn things.