Hello all,

Maybe someone can chime in. I've searched all through alarm issues here and other sites and can not find an answer to my dilemma.

2009 A4 with a non working alarm horn. I have VAG-COM and do have the H12 Communication issue. I have replaced the alarm horn module. I took the old one apart to see if I had the dreaded battery leakage issue but did not have that. Also found out my horn is not in the trunk, but under the hood under the wiper area on the passenger side. Nice hiding spot.

No other codes present.

Also, when I try to lock the doors using the door lock, they will not lock. The FOB will lock the doors.

I can push the panic button on the FOB and the lights flash, but still no horn.

What can I try next?

Thanks!

 

Sounds like a door latch unit. The reason it doesn't sound is because the system doesn't see all the doors as closed.

Even though the MMi may show all doors closed the comfort module isn't.

I am not too familiar with VAG COMs so i don't know if they pick up every Audi specific code. But it usually does throw one for what ever door is malfunctioning. You could try to close the locks manually with a screw driver and checking if the light for the door goes off or stays on

 

Would that also allow the lights to flash if it thought one of the doors wouldn't close? Anyone with a '09 A4 want to test that?

I don't have any other codes pointing to a door or hood/trunk issue.

The H12 issue reported by VAG COM is for no communication to the horn the way I read it. Not sure where the wire goes once it leaves the horn. Goes into the firewall. Possibly it has been disconnected on the other side but not sure where that is.

 

Yes, is the little red light blinking to show system armed when lights flash....?

 

I was talking about the blinker lights flashing. They flash when you hit the panic button on the remote. Just no horn sound.

The red lock light on the door is solid red when I have the doors locked. I have tested all doors to verify they are locked and closed.

I know a trip to the dealer would probably find my problem, but if it just a connector somewhere, I'd love to find it myself.