* The alarm is going off unexpectedly: This often happens due to a faulty sensor, a low battery, or even a short circuit. Check your battery first. If the battery is low, replace it. If that doesn't solve it, you'll likely need to have a mechanic diagnose the problem. The alarm may be triggered by a door ajar sensor malfunctioning, for instance.
* The key won't work (the security light is flashing): This indicates the Passlock system is preventing the vehicle from starting. The Passlock system is tied to your ignition key. There are several possibilities:
* Weak Battery: A weak battery can sometimes interfere with the Passlock system's signal. Try jump-starting the vehicle.
* Faulty Ignition Switch: A problem with the ignition switch itself can disrupt the Passlock system. This requires professional diagnosis and repair.
* Faulty Passlock Sensor Ring: This is a ring inside the ignition cylinder that communicates with the key. It can wear out or malfunction. Replacement is usually required.
* Transponder Key Issue: The chip in your key might be damaged. Try a spare key if you have one. If the spare key works, the original key needs replacement.
* You've replaced the battery: Sometimes after replacing the battery, the security system needs to relearn the key. This usually isn't a formal "reset," but rather allowing the system to recognize your key again. Usually, this happens automatically after you successfully start the vehicle with the correct key. There are no special procedures for a 2001 Blazer.
In short, there is no universal reset button. If you're having trouble, you need to diagnose the specific problem. A mechanic with diagnostic tools is usually the best resource for solving security system issues on older vehicles. Trying to bypass the security system without proper knowledge can damage your vehicle's electrical system.
