Anatomy of your Door Latch, or How Audi puts your car at risk.
 

Last week I posted regarding the door open switch inside my door latch.
I fixed that, but had a chance to take a close look at different problem.

Many TT and especially A4/S4 drivers have complained that their cars were broken into, and the alarm did not go off.
this has been a problem for VW-Audi for a long time.

Here's what happens.

The door lock cylinder is about 3" from the actual latch.
It is a long rod that goes into a slot in the door latch.
If you insert and turn the proper key, the rod rotates.
The door handle operates a small cable to move the door latch.
You can see both of them here.

<img src="http://mk1tt.montebellopark.com/images/latchbar1.jpg">


<img src="http://mk1tt.montebellopark.com/images/latchbar2.jpg">


<img src="http://mk1tt.montebellopark.com/images/latchbar3.jpg">


The latch contains the electrical parts and motor that moves the latch.
Simple electric micro switches, not "electronics" control it.


<img src="http://mk1tt.montebellopark.com/images/latchpcb.jpg">

These switches are trigged by the slot rotation.

<img src="http://mk1tt.montebellopark.com/images/contactpoints.jpg">

The pivot point here is a shaft that moves from the screw drive, though the other side of the back wall that small metal arms get attached to, that move levers and rods on the other side of the door latch.

<img src="http://mk1tt.montebellopark.com/images/latchmechanism.jpg">

Meaning, that if I stick anything in to this slot and rotate it. I can unlock the door and disarm the alarm, because the system thinks I'm a key or the remote key fob.


<img src="http://mk1tt.montebellopark.com/images/latchslot.jpg">

It's dumb.
You could pull the plug and short the wires to open the door.

All you need to do is get a long flat-blade screwdriver; punch it vertically just under and to the inside of the door lock. The rod inside will actually guide you along the shaft to the slot in the latch. Any 10-year old knows how to do this.

Work this hard enough and if you will break the shaft out of the slot being held simply in place by the door cylinder. It's not the cylinders fault. You break the slot enough to dislodge the shaft. And the screwdriver is your friend. The doors open almost by magic.

And the system thinks it's a legit unlock/open.

Wire your after-market alarm contacts to these points in the foot wells, behind the small kick panels. These are the wires to the 'door open' switches.
Even if they disarm you Audi alarm, and unlock the doors, your other alarm will take control.
I have it wired this way on my TT with the alarm system on my remote starter install.

<img src="http://mk1tt.montebellopark.com/images/doorsw.jpg">


People that have cars in high-risk area, you may wish to contact a good alarm installer.

You are amazing.

Thanks for the very informative article. I have to go and steel a TT now, Bye!

that defintely looks weak and flimsy. My A4 has tougher components, but the weak link is punching a
 

hole in the right spot to move the switch rod. I put a hidden switch to disconnect the unlock wire inside the door to eliminate unlocking via screwdriver. I still have the trunk key anyway if my batteries run out, or just have it beep momentarily :) I also have a secret crank button so it's not easy to crank the car, since accessing the starter is pretty much impossible by a theif on short basis anyway.

Good info Jeff. That motivates me to install anti-theft on the TT.

On bad locations, I had taken the TT ECU with me to the hotel room before.

better get a mk1, the mk2s are mostly aluminum

lol. My TT is steelen, I mean mostly steel.

If I have to park in an area where I don't feel comfortable, I put the Club on.

Truly, and that was fascinating as well. Makes me want to aftermarket it and test it in Compton.

thats' a good way to stop it too.

Great sloothing Jeff! The insurance guys will be delighted to hear about this one.
 

Yet another example of inferior VW/Audi parts/component design. The same Audi engineer that spec'd the supplier requirements for the cluster, the horns, the fuel senders, the initial coilpacks, the initial DV's, etc., etc. did this part too!

Nice to know that the only safe place for my car is in my locked garage.

:)