quattrobabe

Finally have the 200 running like a dream and now I have run into another gremlin. How in the hell does this alarm system work?!!? Sometimes it goes off for no apparent reason while I'm driving or trying to start the car. Have looked in owner's manual (doesn't tell you dick) and searched in archives on this site...nothing. The car has a keyless entry that I think is after market, could this be the problem? Although, even when I don't use the remote lock thing I still have problems. Any suggestions would be appreciated.
Christy

Will Ng

The factory alarm gets activated/deactivated by the front door locks. There is a nominally open, momentary trigger that goes to GND when ever you lock and unlock the doors with your key.
This trigger goes to the factory alarm unit.

The keyless entry unit should be wired to trigger a relay connected to GND and spliced to the trigger wire mentioned above. This will allow you to use either key or keyless and still use the factory alarm.

Right now, it sounds like once you've locked the doors with a key (and armed the alarm). Upon unlocking with the keyless method, you set off the alarm the moment you open your door. If the alarm is armed, you shouldn't be able the crank the starter.

Another explanation is that the trigger assembly in the door lock is faulty and it's arming/disarming erratically.

I've posted the pages on the 89-91 100/200 factory alarm from the Audi tech training manual at my website. Follow the Audi link.<ul><li><a href="http://members.fortunecity.com/willng/audi.html">http://members.fortunecity.com/willng/audi.html</a</li></ul>

Will Ng

There are 2 wires going to the factory alarm unit. 1 to arm and 1 to disarm. You'll need 2 relays with your keyless remote system. Use its 'lock/unlock' outputs to drive the relays.

HTH,
Will