Alarm beep

[Duchenbagen]

I am having an issue with the alarm module in the trunk not beeping when the car is locked. All the doors, hood and trunk are closed. I bought a replacement unit off of eBay. It didn’t work. So, it was returned. I ended up biting the bullet and buying a new unit from the dealer for $269. It’s installed and still doesn’t work. I have searched the web and it seems like everyone else was able to solve this with a new module. I scan the car and get this:

Fault Codes
1 Fault Found:
01134 - Alarm Horn (H12)
49-00 - No Communications

What else can I look at. This is a really annoying situation. I just want to put my trunk back together and have a confirmation that the car is locked and the alarm is armed. Thanks in advance.

[Gunnarrrrr]

since you’ve already tried a new alarm horn (H12) it’s time to isolate the issue to either wiring, or the comfort module (j393) itself.

take the good alarm horn, and connect pin 3 to 12v, pin 1 to ground, and pin 2 directly to pin 7 on the black 12 pin connector on the comfort module, should be a black/yellow wire currently in its place. You can get to the body control module without removing the carpet fully, just pull the lower plastic around the door frame and unbolt the driver seat and rock it back.

Here’s a page from the wiring diagram to clarify:




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[Duchenbagen]

Awesome man! Thank you, I was thinking about making an overlay and doing this. Just what a pain in the ass. I bought this just in case it’s the harness: 1J0973703

https://a.aliexpress.com/_mMUhTIj

[Turbo510]

My '05 also has had the alarm quit, but I've got a different take on this. There's a good chance that the NiHM batteries in all of these alarms - your original, the Ebay part, the Audi dealer part and mine are all bad. Batteries installed when Bush was the president likely don't charge, and leak even if still in the unopened box. Here is one video which I watched explaining how he replaced the OE battery set.

youtube.com/watch?v=DEb4b5aSnO8

[Kevin C]

FYI, when the battery fails it takes out the connector and part of the harness. The wires on mine were corroded several inches up the harness and the pins no longer made a good connection. I picked up a pigtail from the yard that had not leaked. B7's use the same basic unit and connector.

If anyone is sourcing used units on Ebay (8L0951605A is the latest rev)


There is a code number on the alarm. Higher = newer. 78xxx is typically 2008.


Code # VS Year. Codes from various horns on Ebay vs what year car they came from.
78507 2008
78720 2008
79212 2008
79205 2008
78720 2008
78410 2007
68719 2007
68302 2006
58705 2006
48529 2005
48531 2005
48910 2005
48910 2005
49819 2005
49130 2005
39123 2004
39217 2004

[Turbo510]

FYI, when the battery fails it takes out the connector and part of the harness.

Evidently not in all cases, as it didn't in the case of the guy with the Avant 3.0. He replaced the PCB-mounted OE batteries with a new external 7.2V battery pack. I haven't checked mine yet, but now I'm curious.

[Gunnarrrrr]

before I learned my lesson to find a good one and immediately pull the batteries and replace them, I lost two to leakage and never had any damage to my harness. I’m on the third one now with oem nimh varta batteries mounted outside the housing with no problems.

also btw, b8/8.5 alarms are compatible with our cars as well. downside is they’re mounted outside the car next to the brake master cylinder so used ones are typically in even worse shape than a used b7


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[Kevin C]

Evidently not in all cases, as it didn't in the case of the guy with the Avant 3.0. He replaced the PCB-mounted OE batteries with a new external 7.2V battery pack. I haven't checked mine yet, but now I'm curious.

My bad... It should have put it often takes out the connector. A good rule is if the PCBA in the unit is badly damaged, so is the connector. At some point the connector gets intermittent and you need a pigtail to make it work. Thats what happened on mine. I replaced the unit with a good used one and it still would not work. Once I swapped the pigtail it was fine. When I cut the wire back it was amazing how far up the cable the corrosion had traveled.

When I re did mine I also conformal coated the PCBA.

[john_gonzo]

When I cut the wire back it was amazing how far up the cable the corrosion had traveled.

Same. I moved the batteries to the other side of the car. Can check/change them without tearing apart the trunk. No more corroded alarm circuit board. A few pics here: https://www.audizine.com/forum/showt...=1#post9773552

[Kevin C]

Same. I moved the batteries to the other side of the car. Can check/change them without tearing apart the trunk. No more corroded alarm circuit board. A few pics here: https://www.audizine.com/forum/showt...=1#post9773552

If it corrodes the circuit board from there, you have bigger problems.

[Gin+]

I just picked up a siren from a newer b8.5 PN# 1K0 951 605C. I was under the impression that they worked as a drop-in replacement for the older ones, but I'm not seeing any sign of activity. Upon digging, someone mentioned they have a different pinout. Anyone have any idea before I return it?

[Gunnarrrrr]

I just picked up a siren from a newer b8.5 PN# 1K0 951 605C. I was under the impression that they worked as a drop-in replacement for the older ones, but I'm not seeing any sign of activity. Upon digging, someone mentioned they have a different pinout. Anyone have any idea before I return it?

Pin 3 is Constant 12v for both

For the b6/b7, Pin 1 is ground, Pin 2 is the connection to the comfort module. For the B8, its flipped. Pin 2 is ground, Pin 1 is the comfort module connection.

[Gin+]

No kidding, that adds up. Thank you!

[BumblebVR6]

I just picked up a siren from a newer b8.5 PN# 1K0 951 605C. I was under the impression that they worked as a drop-in replacement for the older ones, but I'm not seeing any sign of activity. Upon digging, someone mentioned they have a different pinout. Anyone have any idea before I return it?

Pretty sure that's the one I'm using w/o issue. Same one they use in Lamborghini models I believe as when I ordered it on eBay, that's what the yard selling it had it listed under.

[Gin+]

I give up, still no communication. Guessing defective module.