How to Reset a Security Alarm System

Need to reset the security light in your car? If the security light is blinking the immobilizer system is enabled and will not allow the car to start.

What Goes Wrong?

Most cars today have a security system built into the electrical system (BCM - Body control module) to deter from theft. The problem is it can sometimes stop the person that owns the car from starting the engine as well. These anti-theft systems can sometimes get the operational sequence out of sync which makes the system think the car is getting stolen epically after a repair job. This can sometimes happen when there is no one in the car but the window is rolled down while the car is locked. Someone will reach their hand inside and unlock any of the doors. Another common way for the system becoming triggered is to simply disconnect the battery to install a new unit, or if the battery is allowed to go dead and then jump started. These can sometimes cause an electrical surge triggering the immobilizer system.

How Does it Work?

Car alarms are designed to prevent burglary of the car and warn the owner if a theft attempt is being made. Usually a car alarm will output a high pitched sound when the system is triggered by vibration, closed or opened trigger switches or sensing of small and fast changes in battery voltage. Car alarms can also monitor sensors like infrared, microwave, ultrasound or tilting of the vehicle in the case of unauthorized towing. Some cars have alarm systems which send out SOS signals to a cell phone number in case of breakdown or theft. Alarm systems are also incorporated within a navigation system to increase the security of the car, the navigation system will send out a ping signal so the car can be received.

The security system can also be used to locate the car in large parking lots by using the conformation chirp on the remote fob. Sometimes a car alarm can give out a false alarm when it feels vibrations of thunder or a passing truck. Sensors need to be adjusted properly otherwise it can trigger the device even when a person accidentally touches the automobile as well.

Security systems utilize a remote controller (key fob) so a user can disable the alarm from a distance. The remote control feature is very convenient if the system is triggered by a false alarm. A key fob can integrate a variety of functions such as a LCD screen option which can project the image of a part of a vehicle that is under threat by a thief is one example.

Can I Bypass My Car Alarm?

A simple response to this question is no most cases no. Security systems are designed throughout the main PCM and BCM which control a major part of the vehicle's operating system. Until this system is enabled many systems such as fuel and ignition are shut down.

What We Did

We called name brand dealerships and told the service writer, (who sometimes got us a technician) a car we bought from them is in the parking lot with a mom waiting to pick up her kids from school with the alarm light flashing and the car wont start, this worked pretty well. We have noted down their responses. Hopefully you can gather enough information from us and them to get your car going again. We have noticed popular similarities in almost all cars which are pretty generic which we have listed below.

Security Reset Instructions

This is a generic alarm immobilizer reset procedure and it applies to most vehicles.

Step 1: Drivers Door Key Reset

Exit the car with all doors closed and the windows rolled up. Also, close and any rear doors such as the trunk, rear hatch and front hood. Lock the car using the drivers side lock and walk away from the car at least ten feet. Wait for fifteen minutes and unlock the door, this should reset the security system.

insert door key

Step 2: Activate the Key Fob

Many manufactures will not allow the car to start when the panic button has been pushed. Hold down the panic button for five seconds to reset the immobilizer.

key fob panic button

Next, push the lock button two times and wait ten feet away from the car for ten minutes.

key fob lock button

Then hit the unlock button on the fob twice this should deactivate the security system which should be accompanied by exterior lights flashing or an audible horn beep.

key fob unlock button

Each of these steps should be followed by the cancellation of the security light. If this light is blinking while you are trying to crank and start the engine the system is not reset.

security warning light

Step 3: Turn the Ignition On

Many immobilizer systems need to see the power utilized from each power input delivered from the ignition switch. Insert the ignition key and turn it to the on position and then attempt to start the engine (crank over), the engine wont start. With the key still in the run position wait 10 minutes and the security light should blink and then go out. Turn the key off and wait 5 seconds. Repeat these steps for a total for 3, 10 minute cycles. The car is now ready to relearn the Passlock code the next time the key is used, any trouble codes will clear after 100 cycles of the key.

ignition switch on

Step 4: Remove the Alarm Fuse

The alarm fuse is located in the fuse panel of most cars. Using the owner's manual remove the fuse which will power down the security system. At this point the car will not start, reinsert the fuse to reactive the system. This is known as a soft reboot of the immobilizer.

remove alarm fuse

Step 5: Disconnect Battery

Sometimes the anti theft system can out of sync due to a voltage spike or an operational error. Start by removing the battery's negative cable and leave it disconnected for five minutes then reconnect the battery. This will allow the security system to perform a hard reboot and reset the alarm protocol to help the immobilizer start working in the proper sequence.

disconnect battery

Acura and Honda Security System Reset Information

We called the dealer and this was their response: Unlock the car with the key fob then get into the car and close the door. Insert the key into the ignition and turn the key on and wait for 90 seconds. If that doesn't work raise the hood and disconnect the battery from the negative terminal. While the key is in the ignition and in the on position reconnect the battery. If there is the Honda added security box installed at the lower left side of the kick panel turn the ignition key to the on position. Locate the small button on the box and hold it down for 90 seconds and the alarm will disable.

Audi Immobilizer Reset Instructions

Call to the dealer, this was their response: With the ignition key try to start the vehicle. Exit the vehicle and lock all door with the windows up, then unlock the doors using the key fob the engine should start. Disconnect the battery using the negative cable wait one minute and reconnect.

BMW Alarm Reset Procedure

Call to the dealer, the service writer got us one of their technicians to help us and this was his response: unlock the vehicle with the key fob twice to recognize the key is valid. Push the panic button twice to disable the alarm. Roll the windows up and lock the car. Let the car sit for five minutes while being more than 10 feet away then unlock the car. Do not disconnect the car battery because the alarm system has a rolling code that may get mixed up when reconnecting the battery.

Dodge Chrysler Jeep Alarm Reset

Call to the dealer, this was their response: Disconnect the battery for one minute and then reconnect the battery this should reset the immobilizer system. To disarm the alarm system press the unlock button on the key fob.

Cadillac Chevy GMC and Other GM Security Reset

Call to the dealer, this was their response: Exit the vehicle and unlock the car using the key fob. Insert the key into the outside door handle and turn it right and then left to lock and unlock. This can be done to either the driver's or passenger door. Insert the ignition key and crank the engine over. Hold the panic button down to disable the alarm. Push unlock button and try starting it. If that doesn't work disconnect the car battery by removing the negative cable end. The pass lock sensor that controls the security system is built into the key tumbler or tumbler case which reads a chip inside the key. This chip is generally unseen.

On older GM cars two small wires will break near the tumbler which will activate the system. In this case the tumbler must be repaired or replaced.

Ford Lincoln Mercury Reset of the Immobilizer System

Call to the dealer, this is their response: Hold the panic button on the key fob for 2 seconds. Close all of the doors and while using the key lock and use the key to unlock the lock the driver's door. If that doesn't work remove the negative battery cable for 15 seconds and reconnect.

Hyundai Security Reset Method

Call to the dealer, here is their response: Hit the unlock button on the fob three or fours of times and press panic button once. Lock and unlock the driver's door using the key.

Mercedes Benz Alarm Reset Method

Call into the dealer, this is their response: Install the key in the ignition and turn to the unlock position unlock. Using the key fob hit panic button. Remove the negative battery cable for five minutes and reconnect.

Nissan Infiniti Security Reset

Call into the dealer, this is their response: Using the fob hit unlock button. Use the ignition key to start the car. Use the key to unlock the driver's door. Remove the negative battery cable and then reconnect.

Toyota Lexus Immobilizer Reset

We called the dealer here is their response: Lock the car and shut all doors, then use the key to unlock the driver's door. Push and hold down the panic button on the remote. With no one in the car lock and unlock the car using the key remote. Disconnect the battery and reconnect as a last resort.

Volkswagen Security System Reset

To deactivate the anti-theft system use the unlock button on the remote key. Unlock the driver's door using the key and then switch the ignition switch to the on position. If that doesn't work exit the vehicle and roll up all windows, then use the key to lock the driver's door. Wait for fifteen minutes and unlock the drivers door using the key, start the engine within 15 seconds of opening the door.

To see alarm system questions and answers please visit our forum.


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