Volkswagen Jetta Security System

in Volkswagen
1996 VW Jetta. Recently the electric door locks are unlocking while I am away. I have tried to lock them manualy and also using the electric button. However when I return to the car it is completely unlock. Does anyone have a suggestion?
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Also, I thought that pressing the button on the keyfob ONCE sets the alarm... has VW changed the way the keyfobs work?
The only double-click on my keyfob is to UNlock all doors. (otherwise only drivers door unlocks)
I don't think it has changed, we lock all doors with one press on our 2005.5 and there is a little chirp. I assume that when all doors are locked the alarm is set...is that correct? Alarms are not something we would ever worry about, those things are just an annoyance as far as I am concerned, we just want the doors locked.
Actually - I beleive that all the doors can lock and the alarm may NOT be set.
The way to KNOW that the alarm is "armed" is to see the blinking indicator on the top of the drivers door. (The A4 vehicles have the indicator there... your A5 may have it in differnt location.)
I checked and our manual says:
"Activating the alarm system - Lock the vehicle"
If you are lucky, a previous owner has written the battery code in the ownersmanual. If not, then you need to pull the radio and get the serial # from it.... and VW dealership can decipher the code from that.
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Now - as for starting and immediatly quitting. You are correct in assuming that it is the "immobilizer" which behaves like that. This is NORMAL for the immobolizer to 'forget' the SKC (Secret key Code) if the vehicle is not started for several months.
The security system on VW is based on the Mercades-Benz design which is nearly impossible to bypass. (You car cannot be stolen by starting the engine!) You MUST use a key which is both cut correctly for the keyhole and satisfies the immobilizer built into the dashboard electonics. (simply cutting a key to fit is not good enough)
Some people with your problem have reported that they left the key in the ignition with ignition on for about 10 minutes.... and the immobilizer light was now extenguished. They could then start the engine.
Others have reported that the computer needed to be "rebooted". I am not sure what that means
There is a very slight possibility that the reciever (ring around the ignition key-hole) is defective.... but that is the best advice I can give you.
There is a way to temporarrly "bypass" the immobilizer. There is a step-by-step procedure which involves using the tripmeter to input a secret code into the computer. The secret code is provided by a VW dealership with the following prerequsets;
*)Customer must provide proof of authorized vehicle operation/ownership with vehicle documents and identification.
*)Key tag with covered secret number is available.
*)Mechanically correct key available.
Perhaps your problem with starting and staying running is NOT the immobilizer at all. Perhaps you need to check for airleaks in the fuel system. Sitting unused for several months may have dried out the seals in the injector pump so it is sucking air.
Good luck!
I'm wondering, to avoid paying for a new lock sensor, is there a way I can just disable the alarm? I've heard that the alarm unit is behind the light switch in the dash.
One can often detect which door has the troublesome switch with a VagCom. Unfortunatly, to get at the switches, the entire guts of the door need to be taken apart.
I realize this does not answer your question... but thought you may wish to know more about the problem you are encountering.
The disarm in the trunk works. If I use the key back there to open the trunk it will disarm the alarm, then I take the trunk closed sensor away from the trunk and leave it open, the security should never arm again because it will always think the trunk is open. Is there any reason that wouldn't work?
Also, beware that if you do try to "fool" the security system in the way you are describing, you may end up with a perminant "door opened" indicator on the dashboard.
Be VERY careful that you do not mess with the "immobilizer" circuits. The alarm may be annoying... but the "immobolizer" will simply kill the engine and you will be stranded. The alarm and the immobilizer are both part of the security system and they may be tied together in some ways.
If you really are considering messin with trying to "bypass" the alarm... why not go ahead and just fix the microswitches in the door and be done with it?
There are several step-by-step procedures on the internet showing how to replace the door switch microswitchsx ($3 with Radio Shack part)
http://forums.tdiclub.com/showthread.php?t=77648
Removing door panel
http://forums.vwvortex.com/zerothread?id=1015107
Removing front door parts (from thread above)
http://forums.vwvortex.com/zerothread?id=961163
Thanks for the advice about the imobilizer. I tried my idea last night with the hood actually. It seemed to work for about 5 min, so I buttoned up the door rag and 2 min later I went to move the car and it armed again.
I read the switch replacement post, but as with the hood sensor, I find myself asking... if there's just one plug that gets both the open and closed signal, why don't I just unplug it and disarm with the trunk to never have to mess with this thing again. It sounds like a major PITA to get the door pannel off, then get the lock assembly drilled out from the rivvets, dremmel tools....I just hate security and if I can get it to never come on, I'd be happier.
Also, if I were to know where the keyless entry module is for the car, and it's not a $500 part, I MIGHT be interested in replacing that as it's probably not ordeal this is and I'd get my keyless and security problem fixed as I'd be able to dissarm with the keyless.
I've asked around and gotten 3 different answsers on this, where is the alarm horn on this car? Its a 2000 Jetta base model, a GL I believe. If I were to just unplug the horn and ignore the alarm altogether, would that trigger the imobilzer? I've heard that 2000's don't have an imboilizer, is that true, and is there a way I can verify that on my car?
Thanks to everyone for the advice!
Wes
I beleive the "alarm horn" is one-in-the-same as the normal horn.
Not certain about the 2000, but my daughters 2001 DEFINATELY has an immobelizer. She has complained about the engine starting and the immedeatly shutting down. (this is how the immobelizer works)
When I hooked up my VagCom and ran diagnostics... the onboard computer reported that the immobelizer had been "triggered" reciently.
Does anyone know what I should do? Do I need to re-set the security system somehow?
Here's my problem in short: If the car doesn't arm itself (i.e. the chirp/beep doesn't occur when you lock the doors, though the doors are locked) the next time I attempt to start my car, it will work for a bit (about 2 city blocks) and then shut down. It will not start again, and only when the car decides its good and ready to "arm" itself (i.e the chirp happens) and I wait 10 minutes, does the car start, no issues, and everything is A-OK.
Information about my car:
2000 Volkswagen Jetta, probably the 2000.5 version, its the newer style body. The driver side door was knocked into by a ConEd van a while back, but before I owned the car. The doors close normally, and everything works save for a whistle when driving on the highway with the window down.
I've read about it being door sensors, but is there anything you know to help "reset" the alarm so it will arm itself again? Any other possible causes? Thank you for all your help!
PS if this is in the wrong forum I apologize, this is my first post. Thank you once again!
Do not forget that both the HOOD and the TRUNK also have sensors. If either of these are 'sensed' as not being closed, then the alarm will not arm.
Also, I believe there is a 'trunk open' lite on the dashboard and it is not lit.... so perhaps the only thing left you need to check is the HOOD sensor.
Thank you for the response. I actually got the car fixed, turns out it was something called the "comfort control module" when that breaks, the car didn't think it was armed, and then wouldn't allow me to turn the car on because the system was fooled into thinking someone was stealing the car!
-crimsonashes
BTW: The "Comfort Control Module" in my Jetta is also known as the "Seat Heaters" - LOL
As for the alarm-system causing your issues - It is possible that when you bought it, you did not get the proper keyfob that controls the alarm. It is also possible that some of the microSwitches inside the doors are flakey. this can really confuse the alarm-system (ie... door is sensed as OPEN and CLOSED at the same time, or LOCKED and UNLOCKED at the same time)
Personally, anytime I negotiate the purchase of a used vehicle, I INSIST that all the proper keyfobs are made available or no-deal! Most used-car dealers will agree to this demand to close a deal.
Also be aware that it is not uncommon for the microswitches in the doors to become troublesome. This can send implausible signals to the computer. (Door open and closed at same time.... etc.) The computer responds by simply not arming the alarm system.
Connecting laptop to the computer-port can diagnose the specific problem.