Need to reset the security light alarm in your car? We are a team of ASE
certified mechanics that have created this guide for you to help save you money
and get you back on the road.
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 detour 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
For people who want added security
for their cars can have a police tracking system
installed with the help of services like On Star. These systems come with an additional cost which is to be paid on a regular basis.
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 in 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.
Generic 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.
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
Next, push the lock button two times and wait ten feet away from the car
for ten minutes.
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.
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.
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 leave it for at least 10 minutes.
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.
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.
Acura and Honda Security System Reset Information
Call to 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 bypass.
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
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
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Article first published 2017-01-26