OT GM car question

My girlfriend has a 2000 Malibu. It has developed a problem where after she stops, it will trip some sort of security system and it wont start unless you turn off the key, then turn it own without starting for I think its 10 or 15 minutes. A mechanic told us to do that and it works but we have no idea what is causing it to do this. It doesn't have a security system added or anything its some sort of built in thing. I would be greatly appreciative to anyone who can give me an idea of what could cause this.

Thanks for all your help.

My 2000 Grand Prix does the same thing. The key has a chip in it. We have a spare key that isn't "matched" to the car so it only lets you start it in an emergency and the you have to go through the reset that you described.

The Malibu has GMs Passlock II security system. There is nothing in the key on this one but when a key is put in the ignition, a resistor value specific to your car is sent to the vehicle's computer that enables it to start. If the computer does not get the resistor value, it assumes that someone is tampering with the ignition system by hot wiring or by destroying the ign. switch and it will not start. This is likely caused by the ignition tumbler wearing out and not providing a proper contact where it is needed. GMs of that age are notorious for that. It can be bypassed permanently by a competent technician. GM may even have a bulletin for it. I install remote car starters and I know what I would do. Read the resistor value and put a resistor (or combination of resistors) across the security wires with a relay so that every time you start the car it will get the proper resistance.

The 2000 Grand Prix has PK3 security which has a transponder chip in the head of the key. Unless the proper chip is recognized (by an RF signal sent from the key head when inserted in the ign.) the car will not stard. A little more advanced than the Passlock II but every bit as frustrating when it does not work. If you have two factory original keys that will start the car, you can likely program a third. If you only have the one that will start the car you would have to get a dealer to program another one for you..........$$$$

We had a similar problem with our 2000 Blazer. It would refuse to start, although it would crank and would fire as long as you gave it starting fluid. I took it to the dealer and the service manager immediately said "bad ignition switch". I didn't believe him but he was right. It was the Passkey system.

I'm betting if you check the DTC's, you'll find a B2956 in the BCM. Nearly always ends up needing a new Passlock sensor and ignition tumbler. The ignition on without starting is waiting out the antitheft tamper mode. Once the problem is repaired, reprogramming ign keys is easy. Start the car with the original key, then as quickly as you can, swap in an unprogrammed key and start the engine. The BCM will learn this key up to 4 total. Fords are the only ones I know of that require at least 2 keys programmed for their security system to allow them to start.