Hey Joey,
The ambient light sensor is connected to the #3 connector. Something I am VERY familiar with. It is also related to the ear speaker and the proximity sensor. The thing about that, the ambient light sensor NEVER turns the backlight OFF. It will dim it but never turn it off. I would check your #1 connector and see if there is any corrosion. Take a pic and send it to me (or post it) and I can tell you if there is a chance that it could be repaired. I have refurbished these connectors before. Usually it is the 2nd or 3rd bottom pin from the right that has the corrosion, causing backlight issues.