Buick LeSabre security light?

does your ignition key have the small resistor pellet in it? if yes, then there is a evolving problem with the integrity of the ignition lock cylinder. under normal circumstances, if the cylinder fails when you try to start the car, you will get a no crank no start condition. if the cylinder fails when the vehicle is already running, you will get a solid security lamp, and the vehicle will start the next ignition cycle. look for a code B2960 security system incorrect but valid. needs a passlock sensor. it is by far a unanimous fix for these vehicles.

The security, antitheft or lock picture/icon is a visual indication that something in the car's antitheft system is failing. In most GM cars and trucks there is a hidden system that most people are unaware even exists. From the moment you put your key in the ignition, there begins a constant line of communication between your key's security chip or transponder, to the ignition's lock cylinder, and then to the car's TDM (Theft Deterrent Module). These 3 parts are in CONSTANT communication. If the key is in the ignition, then these parts are sending signals to each other. The security light illuminates when that signal gets broken, even just for a second. When the signal breaks, the car misinterprets this as an attempt at theft and goes into antitheft mode. The car thinks its being stolen or hotwired because it is not getting that signal from YOUR specific key. This is why the security light turns on and shuts down your vehicle. This link explains it pretty well.

http://www.diy-gm-security.com/

The security system in these GM vehicles is a known high failure point. When the light goes on, it stores a trouble code. Eventually these fail and the car will start and then quit. The most common cause is a bad lock cylinder case that houses the anti-theft mechanism. See post below

http://www.ricksfreeautorepairadvice.com/repair-to...

Chip on the key could be dirty, clean that with alcohol as was said. The "turn ignition off, wait, then..." procedure the other guy listed will you get past the security system. If the cleaning doesn't help, try a second set of keys if you have them. That will prove whether it's the key or the ignition cylinder. Problem stops: key. Problem continues: ignition switch not reading the key right.

Hi would a nissan pathfinder have a similar security system?