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Toyota Highlander Alarm Not Working/Keeps Going Off

The day I found my Toyota Highlander’s alarm silent was a day filled with unexpected quiet. It’s like planning for a big, booming fireworks show, only to be met with silence when the fuse is lit. Have you ever approached your car, expecting the usual beep-beep of security, only to find nothing but silence?

A Toyota Highlander alarm may not work if the key fob battery is dead. Replacing the key fob battery can restore the alarm’s functionality, ensuring your vehicle responds properly when you press the lock or alarm button. This simple fix can bring the peace of mind that your car’s security system is active once again.

Frustrated male car driver with head on steering wheel

Another reason the alarm might not be working is due to a blown fuse in the alarm circuit. Just as a single blown bulb can leave a room in darkness, a blown fuse can leave your alarm system unresponsive. Checking the fuse box for any blown fuses and replacing them as needed can reilluminate your vehicle’s security features, ensuring your alarm is ready to sound off at the slightest provocation.

A problem with the 12V battery is another reason that the alarm sounds when it is not necessary. This is solved by replacing the battery with a new one.

An old battery will experience a varying voltage after you switch your car off. The alarm system interprets that as someone trying to break into your car and sets off the alarm siren.

To check your battery, loosen the negative terminal and attach a multimeter to the clamp. Then check that the voltage reading is around 12.5 to 12.6 volts. If it is lower than that, then your battery is failing and is due for replacement.

Batteries last about 3 years, after which you should exchange them for a new one. To avoid making a mistake, charge your battery overnight with a battery charger and then check the voltage in the morning. If the battery is fully charged and the reading is correct, you should check the alternator.

A faulty alternator can cause your battery to run down without being recharged while you are driving.

To check the alternator,  switch the vehicle on and, while it is running, check the voltage on the battery. You should see a reading between 13.7 and 14.7 volts. If it is much lower than this, then the alternator is faulty or the drive belt is not properly adjusted.

After ruling out the battery, you can turn your attention to the hood switch and the door and tailgate switches.

The hood switch on older Toyota Highlanders becomes corroded and worn. This causes a short circuit, resulting in the alarm activating.

The solution is to either replace the switch, which is rather expensive, or you can bypass the switch. To do that, cut the wire that is attached to the switch and splice the two ends together. You’ll need to remove the plastic cover and the grill to access the hood switch.

Toyota Highlander Alarm Keeps Beeping

Confused female driver stopped and hands up in the air

It’s great that the Toyota alarm system alerts drivers to open doors and windows, but the constant beeping can become quite annoying.

To overcome the problem of noisy alarms, drivers have become quite inventive.

To stop a Toyota Highlander alarm from beeping when the rear window is opened, it’s necessary to bypass the system by using a metal catch. The alarm beeps when the rear window is open. By placing a piece of metal with a hole in it inside the lock, the system believes the window is closed.

While the window is open, the piece of metal can remain in place. Once you wish to close the window, press the release button to remove the piece of metal and then close the window.

Toyota Highlander Car Alarm Keeps Going Off

Angry male car driver

It is common for older cars to experience problems with their alarm systems and Toyota Highlanders are no exception.

If your Toyota Highlander alarm keeps going off, it is most likely a problem with the hood switch. The hood catch and switch become rusted and the wires connecting the alarm system short circuit. Other than replacing the hood locking mechanism, you can bypass the alarm.

To bypass the alarm, you need to cut the wires and connect them together. To do this you must remove the grill and plastic cover to gain access to the hood lock. Then cut the wires and splice them.

The alarm is connected to the doors, hood, and tailgate switches. Once these switches get old and start to wear out, they send intermittent signals to the alarm system that the door is being opened. Even when the door lock is perfectly fine and the doors are locked, the faulty switch sends an erroneous signal.

To stop the switches from sending door opening signals, spray each lock with WD40 or any other lubricant you have on hand. Be generous with the amount of lubricant you spray into each lock. Be sure to have a rag or two on hand to catch all the drips.

Once the locks have had a little time to soak in the lubricant, open and close the door or tailgate between 10 and twenty times. This will ensure that the lubricant gets into all the nooks and crannies. The repeated opening and closing will loosen up any dirt that may be stuck inside the locking mechanism and switch.

Wipe off any excess lubricant and test the alarm by closing all the doors and setting the alarm.

Toyota Highlander Alarm Goes Off Randomly

Male car driver with road rage

After a few years, all cars develop some other problems with their electrical components.

If your Toyota Highlander alarm goes off randomly, then the most likely culprit is the hood switch. Dirt and debris, together with rust, can cause the door switch to register that the lock is opening when it is still locked. To solve the problem, apply a generous amount of lubricant to the locks.

If applying lubricant to your door, hood, and tailgate locking mechanisms doesn’t solve your alarm problems, then you will likely have to replace the switches in each locking mechanism.

If you discover that it is primarily a problem with your hood switch, then you can bypass the switch by splicing the wires. You’ll need to remove the grill and the plastic cover to access the hood latch.

Toyota Highlander Backup Alarm Not Working

Backup camera screen in car

To avoid hitting objects when reversing, Toyota installed parking sensors in the bumpers.

This helps to avoid objects that are out of your view. But, unfortunately, they can sometimes malfunction.

When your Toyota Highlander backup alarm is not working, you can be certain that they have water inside the fitting. To fix the problem, you should take a can of WD40 or another lubricant, and spray it into the parking sensors. This drives out any water inside.

If you drive through heavy rain or large puddles of water, there is probably water inside the sensors. As they are mounted on the bumpers in a very exposed position, they become waterlogged over time.

Copyright protected article by Know My Auto and was first published on Sep 3, 2022. .

Spraying lubricant onto the sensor helps to dislodge any water that may have ended up where it shouldn’t. After spraying the lubricant, use a cloth to wipe away the drips and test the backup alarm.

Toyota Highlander Security Light Blinking

Crying female car driver with hands over face

With car theft becoming more of a problem every day, it is helpful to give would-be thieves notice that your vehicle has an alarm.

This makes it less likely that they will try to steal your car and they will rather move onto one that is less well-protected.

Your dashboard’s security light serves as an alert for the vehicle’s anti-theft system. When the car’s engine is switched off, the security light flashes to indicate that the security system is engaged. If the light remains on when the engine is running, it’s evidence of a fault in the system.

The light will flash if the battery fails. This will cause the computer not to recognize the key. Replacing the battery sorts out the problem.

When smart keys malfunction, it can result in the alarm system registering an error and alerting you by flashing while the car is running. A qualified mechanic or dealer will have to replace the damaged key and register it on your vehicle’s alarm system.

If the locking mechanism is faulty or if the door switch fails, the alarm system will register a fault and flash to let you know there is a problem.

How To Perform A Toyota Highlander Security System Reset

Confused male guy with hands up in the air

If you have replaced the battery or if there has been a major fault with your vehicle’s door or tailgate locks, you may need to reset your vehicle’s security system.

Resetting the security system on a Toyota Highlander requires that you insert your ignition key and turn it to the run position. Return the key to the off position immediately and repeat the process 5 times. You can then start the car with the system disabled.

To reset the security system, switch the car on and off 5 times in a row.

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KnowMyAuto is the sole owner of this article was published on Sep 3, 2022 and last updated on .