* Incorrect Key: The most common reason is using the wrong key. Try all available keys, including any spares. Make sure the key isn't damaged or worn.
* Dead Key Fob Battery: If your key fob has a remote, a dead battery can prevent the car from starting. Replace the battery in the key fob.
* Security System Activation: Sometimes, the security system activates due to a low battery in the vehicle itself, a faulty sensor, or even just a random glitch. Try these steps:
* Wait: Sometimes, waiting a few minutes can allow the system to reset itself.
* Unlock/Lock: Try repeatedly locking and unlocking the doors using the key fob (if it works).
* Try the Key in the Ignition: Repeatedly turn the key to the "on" position (without starting) – this can sometimes trigger a reset. Don't keep doing this for extended periods, as it could drain your battery.
* Faulty Passlock System: The Pontiac Montana likely uses a Passlock system which prevents starting unless the correct key's chip is recognized. A faulty Passlock system can cause starting problems. This usually requires professional help. Symptoms might include:
* The security light flashing rapidly.
* Clicking sounds from the starter.
* Complete refusal to start.
* Other Electrical Issues: A low battery, a faulty ignition switch, or other electrical problems can also mimic security system issues.
If none of these steps work, you'll need professional help. A mechanic, particularly one experienced with older vehicles, can diagnose the problem and determine if:
* The Passlock system needs repair or replacement.
* There's a problem with the vehicle's electrical system.
* You need a new key programmed.
Important Note: Avoid repeatedly attempting to start the car, as this can drain your battery. If you suspect a low battery, jump-starting it *might* resolve the issue temporarily, but doesn't address the underlying problem.
