2004 Ford Crown Vic baterry light on

Hello, I have a 2004 crown Vic ex-police, ex-cab, battery light came and I put in a new alternator along with a new battery. The light would not turn off and the car does not charge properly. I had the mechanic put in three different alternators and check all the electrical wires and still it does not charge above 12 volts. Anyone thata may have some advice it would be greatly appreciated thanks

Check for a fuseable link!

Either use a one wire hook up.
http://www.nationsautoelectric.com/regulators.html
Or find the wire that excites the field this will be a small wire. On Chevy's with a light the bulb excites the field. And if burnt out they won't charge.
As noted check the fuse able link.

Also fire mechanic!

is an ecm controlled charging system

if fuse links are ok

disconnect alternator connector c102a, c102c, Lt green/ red wire and yelow/Lt green wires. run car at 2000rpm and check battery voltage. Check at battery and alternator output. charging system will run in default mode at 13.5 volts.

If have 13.5 volts; alternator is ok. check wiring from ecm and ecm