Reset a Factory Car Alarm

Although helpful, car alarms often seem like more of a nuisance than an aid. They go off unpredictably, refuse to turn off, and startle the entire neighborhood. Because the safety of your vehicle is important, you can learn a few methods to troubleshoot car-alarm issues. With a few simple processes, you can ensure both the safety and function of your vehicle.

Steps

Resetting a Factory Car Alarm

1. Unlock the car manually. If the alarm remote is not working, use the key directly. Often times opening up the door will stop the alarm. If the driver's side door won't unlock, try the passenger door.
2. Turn on your car. Put the key in the ignition, and turn the car on. If this doesn't turn off the alarm, try turning on and off the dashboard lights a few times without revving up the engine.
3. Utilize common tricks. Factory car alarms have some simple reset protocols to help turn off an alarm. Most of the tricks rely on using the key in the door; simply put, a lot of factory car alarms have a door sensor, so working with the door might be the go-to for a quick fix.
   • Put the key in the driver's door and turn it twice to the right, then twice to the left. Then insert your key into the ignition and start the car.
   • Turn the key into the unlock position and hold it for two seconds before opening the door.
4. Disconnect the battery. If the alarm is still sounding after the initial troubleshooting, you'll want to silence the siren as quickly as possible. Car alarms rely on the electronic component of the vehicle, and disconnecting the battery should both silence the siren and reset your alarm. Open up the hood, locate the battery, and with a wrench, remove the negative terminal. Then reconnect it after a minute has passed.
   • If it is more easily accessible you can also unplug the wiring harness that connects to the car's horn or siren. If the horn or siren gets unplugged it can no longer make noise.
5. Reset the alarm unit. Locate the alarm and transmitter system; refer to your owner's manual for the exact location. Hit the reset switch or turn it off and on.
6. Remove the alarm fuse. This should both silence and take the alarm out of commission until the fuse is replaced. Find the alarm fuse in the fuse box. Remove it, and put the fuse in a plastic bag. You can store it in your glove compartment for safe keeping.
   • If you cannot locate the alarm fuse right away, remove fuses to see if the alarm will stop. Doing this will not cause damage to the car, but make sure you return the fuses after you've determined they are not for the alarm.
   • Some car alarms, when tampered with, prevent a car from starting as an anti-theft function. If you remove the fuse and cannot start the vehicle, you will have to take the car to a mechanic or dealer.
7. Seek a mechanic if problems persist. If none these reset methods work, try speaking with a mechanic or dealer. If they can recognize the issues over the phone, the fix might be simple. However, further diagnosis might be needed in person.

Disabling a Car Alarm

1. Speak with a dealer or mechanic. Disabling a car alarm can be a temporary fix before seeking professional auto assistance. However, keep in mind, car alarms are meant to be anti-theft, and when tampered with, some systems prevent a vehicle from starting as a security measure.
2. Understand the basics of an alarm system. Alarm systems consist of a few components.
   • Control unit. This part is often referred to as the brain because it functions as the command center for the system.
   • Alarm transmitter. This comes in two forms: key-chain remote or the key.
   • Sensors. Alarms vary and can get complex with various sensors such as pressure, door, or window sensors.
   • Siren. Alarms need some type of warning signal; some systems have their own siren component while others are wired to car stereo.
   • Wires. Wires connect the siren to the control unit, the control unit to the fuses, and the control unit to the sensors.
3. Disconnect the battery. Open up the hood and locate the battery. Using a socket wrench, unscrew the negative terminal (-) of the battery and pull it off. This is a safety measure; messing around with a vehicle's electronics can be dangerous.
4. Find the alarm system. If you have a factory car alarm, check in your owner’s manual as a guide. The alarm system is usually under the hood near the steering wheel. If you have an after-market car alarm, it may be installed in any part of the car, but companies usually install them under the steering wheel.
5. Disconnect wires. Some alarm control units have labels for each wire. Removing the wires attached to the control unit and removing the wires attached to the siren are two ways to disable and silence your alarm.
   • Pull the wire of the siren. This will silence the alarm and might be a good temporary fix before seeking professional assistance.
   • Remove the control unit. If you pull out the brain, there will be no alarm in the car. However, depending on the way your car alarm was set up, this might disable your vehicle from starting.
6. Reconnect the battery and test the car. After you pull a wire, plug the battery back in to make sure the alarm isn't going off again. Turn on your car and give the engine a rev. You want to make sure the car can still function.

Troubleshooting Alarm Issues

1. Fix an alarm that starts when you turn the car on. You could need a new battery. Disable the alarm by removing the alarm fuse, and then bring the car to the shop. They can check your battery and move on from there if the problem is the alarm system.
2. Diagnose an alarm that never sets. Lock your car electronically using the remote, if you have one. Push down the locking pin on the door manually if the remote does not engage the lock or if you don't have a remote. Use your remote key or click the "lock" button on the driver's side door to engage the lock. If this does not work:
   • Disconnect the negative battery terminal.
   • Turn the key to on position.
   • Reattach the negative battery terminal.
   • Turn the key to off position.
   • Start the car.
3. Fix an alarm that goes off randomly. Your alarm sensors are poorly calibrated. You'll need to adjust them so that they do not continue to cause problems whenever a dog brushes up against the car. To do so, refer to your owner's manual under the heading "Alarm System." Most cars can be re-calibrated to be less sensitive without going into the shop. There are two types of alarm sensor controls:
   • DIP Switches: These are a series of toggles that control how much electricity runs through the sensors. Turning a few off will make your alarm system less touchy. These are built into the main control unit of the alarm system.
   • Rheostat: Using a small screwdriver, you can loosen up a bolt that adjusts the resistance in the sensor, making it more or less sensitive. These sensors are mounted externally.
4. Check if the alarm is the reason your car won't stop. When a car refuses to start, most people go through a series of checks to find the issue. After all the checks lead to no solution, consider checking the car alarm. Some alarms are wired with the ignition as an anti-theft measure. Attempt to disable or reset the alarm, and then try starting your car.

Warnings

• Only disconnect your alarm or battery as a last resort. You want your alarm there when you need it.
• When working with any car electronics, the battery should be disconnected as a safety measure.

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See also

• Shut Off a Car Alarm That Won't Quit
• Install a Car Alarm

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