How to Reset a Car Alarm

A car alarm that is not working at all or not working properly can be extremely annoying to you and your neighbors. It may also put your vehicle at an increased risk for theft or vandalism. Almost all car manufactures today provide several anti-theft options on their vehicles, including alarms. Alarms have proven to be an effective means of deterring potential thieves and vandals. While this is good news for owners of vehicles with alarms, these alarms, like other electrical components, can go bad.

The following steps will help guide you on how to reset your factory car alarm. While some of these tips may apply to aftermarket car alarms, it’s best to consult a manual if you are experiencing problems with your aftermarket alarm.

  • Note: Do not attempt any repairs you do not feel comfortable completing on your own. Because the alarm system draws power from the battery, you should exercise extreme caution when attempting any repairs.

Method 1 of 5: Resetting the alarm remote

It is possible that the key fob or alarm remote has failed and is not sending a proper signal to your vehicle’s alarm system. When this happens, your vehicle’s alarm may inadvertently end up going off without you wanting it to.

Step 1: Consult your manual. On older vehicles, the owner’s manual may provide a way to reset the key fob or alarm remote.

Most procedures will vary from car to car, but you can try removing and replacing the fob battery.

Step 2: Use a code reader. On newer vehicles, the key fob or alarm remote may need to be reset with a code reader/scanner.

Your owner’s manual may tell you how to complete this reset, though you may still want to consult a mechanic before attempting it.

Method 2 of 5: Resetting the alarm

Some of the more common alarm resets involve less-complicated techniques that can be completed in a matter of minutes.

Step 1: Unlock the car. Sometimes an alarm will deactivate when you try manually locking and unlocking the car.

When the vehicle notices that the key has been inserted into the lock, the alarm may shut off.

Step 2: Start the car. You may also try turning the car on to reset the alarm.

Step 3: Use key to lock and unlock. Try inserting your key into the door lock and turning the key to the locked position and then turning the key into the unlock position twice.

This may temporarily disable the vehicle’s alarm while you drive.

Step 4: Hold key in unlock position. You can also try holding the key in the unlock position for two seconds.

Method 3 of 5: Reset the battery

Resetting the alarm by unplugging your vehicle’s battery can be dangerous so you should use caution when attempting this method.

Step 1: Find your battery. Open your vehicle’s hood and locate the battery.

wrench being used to remove the negative terminal wire

Step 2: Remove the negative terminal wire. Use a wrench to loosen the nut of the negative terminal and remove the wire from the battery.

Step 3: Reattach the wire. After about a minute, reattach the wire.

This should reset all of your electrical systems including those that power the alarm.

  • Note: Disconnecting the battery will also cause your radio to forget presets. Be sure to write them down before removing the battery’s wire.

Method 4 of 5: Replacing the fuse

You may also want to try replacing the fuse that is associated with your vehicle’s alarm.

Step 1: Locate the fuse box. This is typically located under the left side of the steering wheel.

Step 2: Remove the corresponding fuse. Consult your manual to determine which fuse is associated with your car alarm.

replacing the fuse

Step 3: Replace the fuse. Replace it with a fuse rated for the same amperage.

Method 5 of 5: Disabling the alarm

If your alarm is causing a constant distraction, going off often and spontaneously, you may want to disable the alarm completely. Be mindful however, that if you disable the alarm, your vehicle will have one less safety feature. You should consult a mechanic before deciding to completely disable your alarm.

  • Note: Be aware that because some alarm systems work in conjunction with your vehicle’s ignition, meaning that if you tamper with the alarm, your vehicle may not start.

Step 1: Consult your vehicle’s owner manual. To find the correct wires to disconnect, you should consult your vehicle’s owner’s manual.

Resources specific to your car may also be available online.

  • Warning: You should be sure to disconnect the battery on your car before attempting to remove any other wires.

underside of alarm unit showing wire to be disconnected

Step 2: Remove the the wires connecting siren alarm control unit. By removing the wires connecting the siren and the alarm’s control unit, you can disable the alarm until it can be fixed permanently.

While faulty car alarms can be very annoying, it is important make sure there are not deeper issues at work. While these DIY fixes may solve your problem, you should always consult a mechanic if the solution seems more complicated. If you need a fuse replaced or a new battery installed, have one of YourMechanic’s certified technicians come to your home or work to do the job for you.


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