Nissan Repair: Immobilizer Key System, keyless entry system, electric locks

Question
Hello Von,
I just purchased a 2001 Sentra SE.  The car didn't come with  a manual and I just found out that it has a Immobilizer in it. ( Keyless Entry System   I found out by seeing a red light on the dash blinking one night while looking through the windshield.  Since then I must have done something to deactivate it because I haven't seen it blinking although it is supposed to do it just by locking the doors.  Do you have any information on this system and what could be happening?  The car is working just fine but I'd like to know that the immobilizer is working as well.  Thanks much.

Sincerely,
Tim

Answer
Tim,

When the car is off and locked the light flashes.  Only a warning to potential thieves.  Understand that the way this thing works is your key has an electronic device in it that shakes hands with a receiver in the car and that tells the ECU to allow the car to start.  If someone broke into your car, without you key it will not start.  Fuel pump cutout switch keeps the car from starting if they try.  You have to have your keys only.  The other part of the alarm is that if one of the doors is opened or the hood, if you have a pin switch there too; some don't, it will honk the horn and flash the lights.  If the light does not flash that could be the LED not working.  If it was me I would disconnect the battery and reconnect it after five minutes and see if the computer resets.  Otherwise, if the car is locked and the LED does not flash you will need another light.  You can check the alarm if you want by opening the window and then locking the car with either the key or the electric locks.  Wait three minutes and open the door by reaching inside and unlocking the door and opening it.  The alarm should sound.  If not you probably have a door switch out of wack.