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Toyota Corolla Alarm Not Working/Going Off Randomly

If you are doing your best to protect your Corolla and the stuff inside it, you probably have an alarm on it. Unfortunately, from time to time, like with anything else, you may run into some problems. So, what should you do if the alarm is not working properly?

One common issue with the Toyota Corolla alarm not functioning or activating unpredictably is a faulty door sensor. These sensors detect when a door is opened, triggering the alarm. If they malfunction, the alarm may not sound when expected or activate without reason. To remedy, inspect door sensors for damage and replace as needed.

Another reason for alarm irregularities in a Toyota Corolla can be a weak car battery. When the battery voltage drops significantly, it can send erratic signals to the car’s systems, including the alarm. This might cause the alarm to go off unexpectedly. Ensuring the battery is in good health, charged, or replacing it if old can rectify the problem.

Hand pressing car key fob to unlock

Additionally, the key fob used to lock, unlock, and deactivate the car alarm can also be a source of issues. If the fob’s battery is dying or if it’s malfunctioning, it might not communicate properly with the car, leading to alarm inconsistencies. Replacing the key fob’s battery or reprogramming it can often resolve these alarm issues.

The issues included are some of the more common ones relating to Corollas and their alarm systems. We’ll address some possible methods to finding the problem and fixing it, but approach with caution. If you have no clue what you are doing, you could cause some serious damage to your car.

Toyota Corolla Alarm Not Working

Male looking distressed with hands on forehead

If your alarm is going off randomly, chances are, there is an issue surrounding the car battery. If the battery is low or dead, it will not properly power anything, including the alarm. This may require a charge or complete battery replacement.

In some cases, you might also have a sensor issue or have something wrong with a part of the alarm system. This will require you to search through the mechanics for any faulty parts. If you are not confident, it is always better to seek professional help.

If your key fob has a low battery or something else wrong with it, it can send the wrong signals to your alarm system. The easiest fix here is to replace those batteries. You also can reset the fob or even reprogram it.

The control unit of your alarm could also be the problem. Sometimes, electronics just don’t work right, even right out of the box. If it’s gone bad over time, you’ll have to replace it. If it were bad when installed, you’d still need to replace it, but the installer won’t be able to charge you extra for it, so that’s something.

Any of these problems are fixable given the time and effort. Money may be needed if you have to go to the mechanic, but there are a few things to try before resorting to that.

Toyota Corolla Alarm Goes Off Randomly

Asian female using fingers to cover ears

If your battery is low or dead, this can cause your alarm to go off when it shouldn’t. To know if this is the cause, you’ll need a voltmeter, like this Crenova Digital Multimeter, to check the charge. Your battery is considered fully charged if the voltmeter reads 12.6 volts or higher. If your battery reads at anything lower than 12.4 volts, it is low and needs to be charged or, more likely, replaced.

Another battery issue that may interfere with your alarm is corrosion. If your battery terminals are corroded, it will have difficulty sending power out through the terminals, which can make your alarm think the battery is low. Corroded terminals will also cause other problems with your car. Pour some Coca-Cola on the rusty spots and take a Dewalt Wire Cleaning Brush to it. You should be good as new.

Toyota Corolla Keeps Beeping

Hand pressing car key fob

Your alarm system may not be going off randomly, but there are cases in which the Toyota Corolla’s keeps beeping at odd intervals. While it’s not as annoying as your car all-out screaming in the driveway for no reason, it’s usually caused by any of the same issues mentioned in the section above. Check your battery, sensors, and components as you would if the alarm was going off.

You could find another common cause within the latch on the hood. The hood latch of your Toyota has a sensor on it, so the car knows if the hood is open. So does the door, which is how the car knows to beep at you if you leave the keys in the ignition while you’re getting out.

If these sensors are failing, they may trick the alarm system into thinking someone is breaking in or that something has been left open, and you may notice consistent beeping.

Toyota Corolla Alarm Sensitivity

Male holding car key fob

Another sensor issue revolves around the alarm system itself. If your alarm’s shock sensor’s sensitivity is set too high, you can get some false positives.

The sensor is designed to give the car an idea something is wrong if a would-be thief jostles the vehicle while breaking in. But if your cat is setting off your alarm by jumping on the hood, you need to get that sensitivity dialed down a bit at your dealership.

Toyota Corolla Alarm Going Off

Hand pressing car key fob

If you have checked the above, but the alarm is still going off, you might be dealing with bad connections to the sensors. If so, an easy fix is possible. Connectivity can be reestablished sometimes by simply disconnecting and reconnecting the offending sensor. If that doesn’t work, and if cleaning fails, too, replacement may be necessary.

Toyota Corolla Security Light Blinking

Car security alarm light

Some Toyota Corolla drivers find some anxiety in the security light blinking on the dashboard, but this is not usually indicative of a problem. In fact, it’s the opposite – it blinks when the car is off, the alarm is on, and all is well.

The security light briefly flashes when you start the car to tell you that the bulb is working. The only time this light is cause for concern is when it turns on and stays on, which indicates a sensor issue, most likely.

Toyota Corolla Alarm Reset

Car mechanic working on car

Once you’ve repaired the problem – or have realized that you can’t fix it yourself and can’t afford to take it in for professional work just now – you may need to disable your alarm or reset it. A reset may be necessary after a repair so that the alarm’s brain can forget about the issue that doesn’t exist anymore.

The alarm in a Toyota Corolla has a reset actuator under the dashboard on the driver’s side. You’ll have to get down under there and look to find it, but depending on the year, you’ll find either a button or a sliding switch.

Push it or slide it to reset the alarm, and all should be well. It bears mentioning that if you had work done on your alarm system by a professional, they should have already taken care of this for you.

Toyota Corolla Alarm Disable

Car alarm

You may need to disable your alarm if it can’t be fixed, or maybe it just needs to be fixed later. Or perhaps you’ve lost the key fob but still need to drive the car. Disabling the alarm involves less bending and crouching than the reset, but the process has the air of superstition to it.

Put the key in, then switch it quickly from the “Start” to the “Off” position five times. Don’t worry about your car starting and shutting off – you’re doing this because the absence of the key fob or the presence of another issue is causing your alarm system to prevent the car from starting.

Once you’ve done the five “Start”-to-“Off” turns, your alarm should be disabled. Start the car as you normally would, then drive it to your dealer or mechanic and get the alarm fixed. You may also want to remove the fuse or even disconnect the system’s wires (this is not for amateurs).

The copyright owner of this article is and was first published on May 6, 2021..

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KnowMyAuto is the sole owner of this article was published on May 6, 2021 and last updated on .