1991 Audi 2.3 20V. When I got it the previous owner told me that the car doesn't have an alarm and their is no fob to turn any alarm on or off.
Today I left the lights one, I get out of work and it is dead as a doornail. My son brings the minivan up to work and we jump it. When the battery starts charging it starts to come to life. I put the key in to start it and an alarm goes off. It sounds like it is under the back seat. I can not start it and the lights flash and the horn sounds.
I disconnect the jumper cables and the car has the alarm going until the battery dies again with in a minute or so.
Damn. Is there any way to bypass the alarm? All I have is the ignition key.

