What To Do If My Car Alarm Keeps Going Off In The Middle Of The Night

It can be frustrating to keep waking up to in the middle of the night to the sounds of a car alarm.  If your car alarm keeps going off for no apparent reason you may want to do some investigating to see what may be causing this.  

If you are not able to find the ultimate cause of what is causing your car alarm to keep going off you may want to take your car to a mechanic to have them see what they can find.

Main Causes of Your Alarm Going Off

If your car alarm keeps going off when you don’t want it to then there are some basic things that you can troubleshoot yourself before taking your car into a shop to have them check it out.

1. Very Sensitive Aftermarket Car Alarm

If you have an aftermarket car alarm there are sensors that they install on your car that are able to sense if the car shakes in any direction which will then trigger the alarm.  If you or the installer put the car alarm sensor to the most sensitive setting it will sometimes cause the car alarm to go off with just a strong gust of wind.

The good news is that you can usually adjust the sensitiveness of your alarm by reading your owners manual and finding the location of the alarm sensitivity adjustment.

If you did the aftermarket car alarm installation yourself you may want to double-check that you installed the aftermarket car alarm system properly.  

If it was not set up properly and all of the cables were not properly connected this can also cause the system to malfunction. It would be a good idea to go over all of your connections again to make sure that you have everything wired right.  

If you still not get an aftermarket car alarm to stop from going off you may want to take your car to a car alarm or car stereo specialist shop to have them take a look at it. Those guys set up car alarms for a living so they should be able to spot the problem rather quickly.

2. Hood Latch Sensor

If your car is equipped with a hood latch sensor this can also be a cause if your alarm keeps going off for no apparent reason.  If your car’s hood latch sensor is going bad it will think that your car’s hood is unlatched and will trip the alarm to try to prevent someone from getting in your hood.  

The most obvious fix for this clean the existing hood latch sensor to see if that fixes things.  If you suspect that your hood latch sensor is just dirty from being under the hood of your car over time you can first try cleaning it with a brake cleaner spray or something similar.

You just want to make sure whatever you clean it with will have some evaporative properties and not gunk up the operation of the hood latch sensor. After you spray the hood latch sensor with the brake cleaner you can try to wipe the hood latch sensor clean with a rag or microfiber towel.  After you have fully cleaned the hood latch sensor you can then lock your car again to see if your car alarm keeps going off.

The next option would be to replace the hood latch sensor with a new one to see if you are still seeing the same issues.  It is not that hard to replace a hood latch sensor yourself, they are usually only held in place by a couple of bolts. You can buy another hood latch sensor online on eBay if you wanted to try to do it yourself.

3. Faulty Key Fob

If your car has a faulty key fob or an aftermarket key fob that is going out this can also cause your car alarm to keep going off.  If your key fob is not able to send the proper wireless signal to your car causing your car alarm to go off.

If you can check the levels of your key fob you would want to make sure that it is properly charged.  If you cannot check the levels of your key fob battery you would likely want to replace your key fob battery with a new one just to rule that out.

If replacing your key fob battery with a new one still does not help fix things you may want to look at replacing your key fob with a new one.  If you are using the factory key fob you can take your car to the dealership for a replacement key fob. If you have an aftermarket key fob you can most likely order a new one online from the original equipment manufacturer.  

You also have a third option of trying to find your key fob online and then taking it to a dealer if needed to have your key cut.  You can likely save some money by purchasing your key fob online instead of through a dealership.

4. Car Battery

Another reason why your car alarm keeps going off can be your car battery.  If your car battery is old or malfunctioning it will not be able to put out the adequate amount of volts to the car’s electrical system which can cause your car alarm to act up.  

If you have a multimeter on hand you can check your car’s voltage by connecting it to your car battery to read the number of volts that your car battery is reading. Your car battery should read around 12.6 volts.  If your car battery is reading fewer volts than that you may want to take your car to an auto parts store to have them check out your battery to see if it needs to be replaced.

5. Corroded Car Battery Terminals

If your car’s engine is not able to properly connect to your car battery this can cause issues with allowing the current of electricity to flow between both systems.  If your car’s battery terminals are corroded this will not allow your car battery cables to be able to effectively connect to the car battery.

This can cause your car’s electrical system to be confused and potentially interpret your battery to have a low charge which can also cause your car alarm to keep going off.  You can clean your car battery terminals by removing the battery wire connectors and using a wire brush to clean off any corrosion from the car battery terminals.

After you have removed all of the corrosion from the car battery terminals you can then hook back up the wire connectors back to your car’s battery.

Last Resort – Disconnect Your Car Battery

If you are still not sure what is causing your car alarm to keep going off you can always temporarily disconnect your battery from your battery terminals to keep it from going off.  Without power going to your car alarm will not be able to function at all.

This will at least buy you some time to figure out what is going on with your car and keep your neighbors from being pissed at you.  You can then just reconnect your battery terminals if you think you have fixed your problem or if you need to take your car for a drive.

Related Questions

Can a low battery cause a car alarm to go off?  A low battery won’t cause your car alarm to go off on its own.  However, if there is a problem with the battery, your electrical system, or your battery terminals are corroded this can cause your car alarm to go off randomly.

Does a car alarm eventually turn off?  A properly functioning car alarm should eventually turn off once it has detected there are no longer any disturbances.  However, if your car alarm is not functioning properly then it may keep going off because it thinks there is still a reason it should keep going off.

I’d first run through the solutions I outlined above in this article.  If you still can’t get your car alarm to turn off then I would take my car to the shop that installed the car alarm or a shop that can install car alarms so that they could troubleshoot it.

How do I reset my car alarm?  You would first want to find the installation instructions for your specific car alarm.  If you don’t have them on hand then you can likely look them up on the manufacturer’s website.  Once you obtain the installation instructions it should give you directions on how to reset your car alarm.

Can a car alarm drain the battery?  Yes, a car alarm can drain a car battery if it is left on for long enough.  Usually, a car alarm will eventually shut off on its own.  However, if it’s malfunctioning then it may not turn off on its own and can eventually completely drain your car battery.

Can police turn off car alarms?  According to this article from the NY Times, police are permitted to turn off car alarms if they go off for longer than three minutes.  Police will first try to summon the owner of the vehicle.  If they are not able to find the owner then they are then allowed to break into the car to disable the alarm system.

In Conclusion

If your car alarm keeps going off it can be frustrating and embarrassing especially if you have neighbors.  If you have an aftermarket car alarm the most likely cause of your car alarm going off is going to be that the car alarm was set to trigger at a sensitive setting.

Other common causes of your alarm to keep going off is the hood latch sensor, the car battery, and corroded battery terminals. Hopefully now you at least have some ideas of what you can check on your car to keep this from happening again in the future.