Cadillac Repair: wont start, negative battery cable, twilight sentinel

Question
hi my grand pa bought a 1991 cadillac he drove it home so i needed the batterie in the cadillac so i took it for my car so when he put another batterie in the car wouldent start and there is a security light it will turn and start for a second  can any one help me ?

Answer
Hi Gary,

     In all reality turning the headlamps on manually...not using the twilight sentinel...for 2 seconds should remove any extra stored voltage once the battery cable has been disconnected. What I would do is to disconnect the negative battery cable at the battery, turn on the headlamps with the switch for 5 minuets. Then turn off the headlamps and reconnect the negative battery cable. And after that time hopefully the computers and modules have reset. If not repeat the procedure for 30 minuets because sometimes it takes longer.

     That procedure can sometimes reset a vehicle computer just like sometimes a person has to turn off their laptop or desktop because it locks up. Bill