Anti thief device - 1998 Plymouth Voyager

Once the theft deterrent thinks the security has been breached, it will not allow the car to be started.
You might need to have the dealer re-program processor.
Hope this helps.

Check the help links mentioned below :---Relearn Theft deterrent module? http://technoanswers.blogspot.com/2012/01/relearn-theft-deterrent-module.html
---------theft deterrent module Relearning? http://howtobyme.blogspot.com/2012/01/buick-theft-deterrent-module-relearning.html
--------Engine will not crank after relearning Theft deterrent module? http://howtobyme.blogspot.com/2012/01/engine-will-not-crank-after-relearning.html
--------Can car radio code block Passkey anti theft system ?

http://schematicsdiagram.blogspot.com/2011/12/can-car-radio-code-block-passkey-anti.html
Car Factory Alarm will go off? http://repairhelpcenter.blogspot.com/2012/01/toyota-avalon-factory-alarm-will-go-off.html
---------Car will not start security lock out? http://technoanswers.blogspot.com/2011/12/car-will-not-start-security-lock-out.html
---------Alarm will not disengage? http://technoanswers.blogspot.com/2012/01/ford-pickup-alarm-will-not-disengage.html
--------This will help.For more info keep updated.Thanks.