I have a 2008 ford ranger xlt 4x4 4.0 truck. we changed the motor and sense the battery was disconnected the anti theft system locked down how do we unlock it.

check key --ignition cylinder--ignition switch for excessive wear -- damage -- failure

Disconnect the battery terminals and wait 5minutes reconnect them when the alarm sounds use your keyfob to turn it off you should be out of theft mode and functioning properly

I've tried the battery trick ??? That's no trick , anti-theft system problem , nothing you can do , dealer only . No magical fixes

To reset the anti-theft system, follow these steps:
1. You have a little red light on your dashboard-press it to disarm the alarm
2. Try turning the key and moving the shift from park to drive and back, then try starting it again
3. Disconnect the battery and let it breathe for 20 minutes and more, and reconnect it, that may do the trick
4. If all else fails, you may need to go down to the dealership to reprogram the key

Dealer only . Unless you have ford IDS scan tool ! Disconnecting the battery does nothing for PATS - passive anti-theft systems . Or a mobile lock smith .

Did you try disconnecting the battery for about 10 or 20 seconds? It may only need to be reset. You may also need to replace the batteries in your remote, or possibly try a second remote if you have one. The problem is definitely alarm related.

Ensure you have "ALL" the wires connected and a fully charged battery. Then use your remote to turn off the anti theft devises and your truck should start with no problems. You may have to switch the anti theft device from your old engine to your new one or take the vin of the new engine to the dealer and get the code for that engine.

Try disconnecting your battery cables then wait about 10 minutes. The computer should reset itself. Reconnect the wires to the battery. It is normal for the theft light to blink about every 5 seconds when the ignition key is out or in the off position. This means the system is armed and working properly. Hope this helps. God bless!

Have you verified this system is running the battery down? The system you describe is called the Remote Keyless Entry System (Electronic Time/Alarm & Control System - ETACS Module). It cannot be 'disconnected' without disabling other systems (intermittent wipers, Chime bell, Door Warning, Dimming Off Room Lamp, Seat Belt indicator, remote power door lock/unlock system, etc.)