Check charging system light for 2006 ford taurus

Battery Light usually means the alternator is not charging correctly and needs to be replaced. Check charging volts, it should at 14 volts or very close to that number. If the number is low below 12 then the alternator needs to be replaced.

Note: A bad alternator can damage the battery & vise versa

I looked at info for your security system, it is starter motor disable. I didn't see 06 ford Taurus in my database, so I looked at 05.
Battery has a full charge and battery connections all good?
We can usually do some tests to see if starter motor will crank the engine, but, if the security is the problem, it still won't start.
You can check for applicable trouble codes? Try a different key?

What error message are you receiving? If you are talking about your check engine light (CEL) then you will need to clear the codes for it to go away, or it must be driven through a series of specific events for the computer to clear itself, just take it down to your local auto store and have them scan and clear codes. At 14.5v you should not get the battery light, you may want to check your wiring to your ECM. With your old alternator running at 16v I would say it is possible something was damaged. I know many manufacturers do not protect the computer from spikes from alternators, I have seen this twice in the field, and actually had personal experience as well. This will require much more knowledge about your vehicle and electricity to understand what pins to test and what you should be looking for.

thee wire that does back to the battery runs to starter. check that wire

Hi:
The check battery light means that your car is running off the battery, and the charging system is not working. A good plan would be to recheck your battery cables and connections, then remove the alternator and have it checked. Most autoparts stores will do this for free. The alternator is the most likely suspect!

check alternator, could ther be a short some where?

check the alternator fuse and grounding

if the car is charging and you have power and ground to the alternator and in the plug then the alternator needs the rectifier either resoldierd at the stator connections or it needs to be replaced.

Check for damaged or corroded wires on alternator. Also check connection to alternator, take off and clean. Alternator may be on it's way out. You might want to get it tested at garage or replace if problem persists.

Where did you buy alt,have had several issues with alternators from auto zone,But check belt tention and idle speed.