Funny thing..

[Circa1990]

So my car has had a dodgy after market alarm since the PO "lost the original key fobs". I've been living with my roommate for a year now, and we both drive mk4 golfs. This weekend his key fob randomly started unlocking both cars and sets my aftermarket alarm off now. Anybody ever heard of this before? Any ideas?

TL;DR My roommates key fob unlocks both our cars wtf

[dwvw]

Re: Funny thing..

So it's his factory fob that is doing this? Not sure if you can recode with VAGcom, or a dealer, but that's all I could think of.

[B4NE1]

Re: Funny thing..

I've heard of this happening a lot actually. From what I've been told it happens most to VW's that are near each other often for long periods of time.

[Circa1990]

Re: Funny thing..

Hmm interesting. Yes its coming from his factory key fob.

[witchcraftz]

Re: Funny thing..

It happens with any car:

The alarm and keyfob actually have a memory of 256 preset "handshakes" associated to a specific position in memory.

Everytime you press the keyfob your car is trying to match the handshake to the right position.

If you have two cars with the same handshake system parked next to each other and you are using your keyfobs, you will end up matching one handshake position somewhere for both. After that they will be in sync until there are no more positions that are identical to both.

Note: this also means that if you press your keyfob unlock button more than 256 times without your car being within range to answer, your keyfob will become deprogramed and you'll have to re-associate it with your car. :P

[P Arkus]

Re: Funny thing..

Note: this also means that if you press your keyfob unlock button more than 256 times without your car being within range to answer, your keyfob will become deprogramed and you'll have to re-associate it with your car. :P

hahaha the retarded part of me really wants to test this, but the common sense part of me doesnt want to deal with the consequences

[Danaldson]

Re: Funny thing..

hahaha the retarded part of me really wants to test this, but the common sense part of me doesnt want to deal with the consequences

hahahahahahahahahahahaha

[CGY_GTI]

Re: Funny thing..

hahaha the retarded part of me really wants to test this, but the common sense part of me doesnt want to deal with the consequences

This alone just made my day! hahahahaha

[eric909]

Re: Funny thing..

That happened to me and now Volkswagen want a butt load to reprogram it!! Stupid idea to put keys in my back pockets...

[witchcraftz]

Re: Funny thing..

hahaha the retarded part of me really wants to test this, but the common sense part of me doesnt want to deal with the consequences

Yeah, well, ask yourself how I found out about this...

[MechEngg]

Re: Funny thing..

That happened to me and now Volkswagen want a butt load to reprogram it!! Stupid idea to put keys in my back pockets...

Can't you just do it if yourself?? I know that if you change your battery in your fob you can reconnect it by a certain procedure....

From vortex:
"there is a set screw inside the door frame that is parallel with the outter door lock. pop off the platic cover. If you back that screw out the door lock will pop out. Once the door lock is out you can use a flat head screw driver to stick in the hole and turn the inside lock to unlock or lock the car. Put the key in the ignition and turn it on, dont start the car. Close the door and have a friend turn the screwdriver to the lock position and hold. While he's holding it press and hold the lock button on the remote untill you hear a honk then release. Then have your friend turn the screwdriver back to the normal position. then quickly press any button on the remote twice. done"

[witchcraftz]

Re: Funny thing..

Yep, I used that technique to progam my replacement keyfob when I washed mine.