* Aftermarket Alarm: The most likely scenario is that a previous owner installed an aftermarket alarm system. The disabling procedure will vary wildly depending on the brand and model of the aftermarket alarm. You'll need to find any documentation that came with the vehicle, look for stickers on the alarm system components (often under the dash), or search online for information based on any visible brand markings on the alarm control unit.
* Basic Security System (Passive Anti-theft): The 1993 Grand Cherokee may have had a very rudimentary anti-theft system built into the ignition system. This wasn't an alarm that would sound, but it might make starting the vehicle difficult without the correct key. If that's the case, you simply need the correct key.
* A malfunctioning electrical component: A fault in a different system might be triggering unexpected warning lights or sounds that you're misinterpreting as an alarm.
To troubleshoot:
1. Inspect for aftermarket alarm components: Look under the dash, in the glove compartment, and under the hood for any aftermarket alarm control units, keypads, or sensors. Look for stickers or markings on these components to identify the manufacturer and model.
2. Check the owner's manual (if you have it): While unlikely to have alarm instructions, it might offer clues about unusual warning lights or sounds.
3. Try the key: Ensure you're using the correct key. Try inserting and turning it slowly and deliberately.
4. Check the battery: A low battery can cause strange electrical issues that might sound like an alarm.
5. Search online: If you find identifying marks on an aftermarket alarm system, search online for that specific model's disarm instructions.
If you've identified an aftermarket alarm and can't find instructions, consider consulting a qualified auto locksmith or car alarm specialist. They'll have the tools and expertise to help disarm the system safely.
