Calling All Wizards!

I have a 1996 Volkwagen Jetta with an alarm problem. The alarm will not turn off .

The key will mechanically unlock the driver’s side door but will not deactivate the alarm. The flashing alarm light on the door stays on after unlocking the door, and when I open the unlocked door, the alarm goes off. I cannot turn off the alarm sound by turning the key in the door in any direction. I am able to shut the alarm sound off by putting the key in the trunk. However, the car remains in a security mode and will not start. Trying to start the car will make the alarm start again.

I’ve contacted the dealership and my usual mechanic and they both have never heard of this situation and can say no more than “we’ll take a look at it.” If anyone has any insight I would be so grateful. Without more info, I’m worried about towing 2 ways for expensive diagnostics that may not be fruitful.

I’ve never had a remote or keyless fob option, just a key, which is a replacement, not original.

I briefly checked the wires in the door boot, hoping to find an obvious culprit, but don’t know what to look for.


  1. After replacing the starter in 2011, the power locks malfunctioned. They could no longer simultaneously lock or unlock all the doors from driver’s door. Could only just lock/unlock driver’s door. In addition, when you locked or unlocked the driver side door, the “motor” sound of the locking system could be heard engaging all the locks …even though they did not all lock/unlock along with driver’s side. This motor sound continued to sound beyond the normal length of time…for about 30 seconds, instead of 2 seconds after the starter was replaced. I never fixed this and this was the status quo of my locking system until the development described above with the alarm… Currently, I no longer hear the motor sound of the locks when I lock or unlock the car, but the lock will still mechanically lock and unlock.

  2. Speedometer/odometer do not usually work. (the mileage and clock do work). Occasionally when there is a significant drop in temperature, the speedometer and odometer work again. They will function again for one trip, but will not work after turning off the car and restarting in the same temp.

  3. Radio stopped working when I had battery replaced

  4. Previously when I was locked out by the alarm in 2007, jumpstarting the car made it possible to drive. Jumpstarting this time just makes the alarm sound.

Would be helpful even just to know if are there mechanics that specialize in electrical issues? Some option other than the dealership or my small garage mechanic.

Is the Check Engine Light on? You might get the codes read if it is. With this many electrical problems, I start thinking about the Body Control Module or Emissions Control Module. But you still need a diagnosis. A VW dealer will have the equipment to test those modules. Other shops may, but ask first.

No check engine light. Thanks! Will probably go with the dealership, but feel I should be as informed as possible before beginning that journey.

Will look up body control and emissions module. Much appreciated!!

Usually the security system, for most cars at least, is activated and deactivated using a key fob. If you don’t have one Ebay is a good place to find used ones at a reasonable price. There may be a procedure to turn off the security system using the key also. My car requires the ignition system be turned on and off three times and the door closed or opened in order to deactivate the security system without the key fob. Perhaps yours may be similar.

As far as your lock system goes I would guess you have some broken wires in the door jam. A common issue with older cars. The wires may be broken and the insulation may be okay so the break may not be obvious. Testing with a meter would tell the story on that. There could be a switch on the door lock that activates the other door lock controls when the driver door lock is opened. The switch contacts may be dirty or the wires to it may be broken. I think those models were pretty prone to electrical problems. I suggest you invest in a factory service manual for the wiring if you want to keep the car. Again, Ebay is a good place to find a manual.

Thanks Cougar! That’s interesting about the on/off procedure. My car never had keyless entry… just the old fashioned key :wink:

I’m really hoping it’s wires in the door, and relieved to hear that breaks may not be obvious. Really grateful for the info about switch contacts and wires too. Will def look into the factory service manual!

Have you tried the passenger side door lock to disarm the system?

There is a switch on each front door latch inside the front doors for the central door locking/alarm system. These switches and wiring can become damaged when using a lock-out tool (Slim Jim). When your starter was replaced did they accidentally lock your key in the car?

Is this a factory installed or aftermarket?

Nevada… thank you!! that is VERY interesting. I lost my own key and a locksmith broke in through the passenger door a few months prior to replacing the starter in 2011. The passenger door lock hasn’t worked since (but didn’t realize until much too late, since I’m never a passenger). All the other locks did work until the starter was replaced.

Barkydog… it’s a factory alarm.

Nevada… i am going to go try that passenger side door one more time! maybe it’s the key :wink:

barky … is factory harder to address?

The power door locks on these cars are pnuematically controlled by a small air pump located in in the trunk area. These sometimes go bad and need to be replaced. If you no longer hear the “motor sound” when you lock or unlock the doors, I suspect this is the case rather than a break in the air line that goes to each door’s lock mechanism. If you get ahold of a service manual, it will tell you how to access the air pump. As I recall the pump runs about $50-60 from the dealer.

As far as the alarm system, I don’t know what to advise, other than seeing if unplugging the alarm module (located under the dash, just above your left knee) will silence the alarm but still allow you to start the car.

Thanks Frontdriver! interesting about the air pump for power locks. I’ve located a manual… hoping it’s legit. Glad to hear your take on the alarm module… was just watching a video about this earlier!

Jetta the factory installed is the best, aftermaket seem to have more issues based on previous posts.

If you go after the alarm module under the dash, as I recall it is a small aluminum box, about the size of a pack of cigarettes. The one in my car was VW oem, but it was “free floating”, just kind of dangling on the cables that plugged into one end. It was very close to the cruise control module, which was anchored in place. I wonder if your alarm module might have a relay which is stuck or has pitted contacts. If you do have a VW oem module, you should be able to get a remote key fob from the dealer or an aftermarket source. It should come with instructions for syncing it to your alarm module.

Which manual did you get? Bentley is the most comprehensive…

Another place to get good advice on the Mk III Jetta is

That’s a helpful description and speculation Frontdriver, Thank you!! Everything is original and I’m the original owner. There was never a remote key or remote alarm trigger. Locks and alarm were always accessed through an old fashioned key. I’m so tempted to dig in and just look at these components, but I’ve also been warned that european alarms are not very nice to deal with.

Thank you for mentioning bentley, too… that is the one I found.

Will check out the forum as well!!