Pontiac GRand Prix 94, will not start. Security lighty comes on. The car acts light no battery or the starter is out. Replaced both but No luck.

Try a new ignition switch.

The security system will prevent the car from starting. Many cars can be reset by turning the car to the on position and then waiting until the light goes off. This can take up to 10 minutes. The problem will happen again. My son has this on his Malibu. We have used compressed air in the ignition and then sprayed the key with WD40 and slid it in and out of the ignition to try to clean the contacts inside. It seems to help but the security problem still happens on an infrequent basis.

Okay, here's what it might be and I have a 94 coupe with 148,000 miles and this was a nightmare. I checked everything from the battery to the starter, no such doing. Under the hood on the driver side you have a fuse box that is almost impossible to get at, if the car will take a jump, then you have the contacts to the fuse box terminal all corroded. My starter had 14 volts, so did the alternator, eliminated those. I would have this checked, even if the security light still comes on..