My VW Alarm Goes off by Itself..... Reasons why its happening
On some Volkswagen models it is not uncommon to have sporadic alarm issues. Often time’s people believe that they have a problem with their keys, remotes or some other part that is associated with their alarm system. Commonly they are under the impression they cause the alarm to go off by itself. The alarm on your VW going off by itself is not likely to be related to the keys or remotes.
This alarm concern is most commonly a result of a failing door latch. The door latches on VW models have a micro switch inside of them that tells the vehicle if the door is open or closed. Overtime the micro switch starts to break down, and rarely completely fails right away. The reason why the door latch failures causes the random alarm problem is due to the micro switch. When the micro switch on the door latch assembly begins to fail it will send the improper signal to the vehicle, causing the vehicle to believe the door has been opened.
For example you have a 2001 VW Jetta, your car is parked in your driveway with the alarm armed. All of a sudden your alarm starts going off for no reason. Nothing hit your car and no one had attempted to break into it. The most likely culprit is your door latch assembly.
Why did this happen?
Most commonly what has happened it your car is sitting with the alarm armed. All the doors are shut.If you have a random failure of this micro switch, it tells your vehicle that the door is now open. Which will set the alarm off as your vehicle thinks that someone has opened the door without disarming the alarm.
The next question becomes "How do I know which door latch is bad?" Your car has more than one door after all. On most current model Volkswagens there is a switch near the from dome light that selects when the interior lights come on. Make sure this switch is on the setting so the interior lights will turn on when the doors in the vehicle are opened. Once you do this all you have to do is open each door on the vehicle a few times to see which door will not turn the lights on.Keep in mind most time the failure is random and will become more frequent overtime.
Once you determine which door does not turn on the interior lights you now have identified the door latch assembly that has gone bad. Most commonly it is the driver side front door latch, as this is the most frequently used door.
Here we have a video installing an OEM VW Drivers Front Door latch on a 2001 MK4 Jetta
Which latch do I need for my Volkswagen?
Please note that this article is the opinion of an individual, and is not a diagnostic of your vehicle. This based on a professionals experience.
Spacing and dashes may be added to the part numbers depending on how you search you may find different results. Other variations include for front latches 3B1837015AS, 3B1 837 015 AS, 3B1837015AT, 3B1 837 015 AT, 3B1837016CF, 3B1 837 016 CF, 3B1 837 016 CF and for rear latches 3B4839015AM, 3B4 839 015 AM, 3B4839016AM, 3B4 839 016 AM, 3B4839015AP, 3B4 839 015 AP, 3B4839016AP, 3B4 839 016 AP