Ultrasport Project EP2: Alarm Siren Module Problems!

In episode #2 of our Audi Ultrasport project, we discuss a possible oil pressure issue and then move on the next big problem: The alarm siren keeps going off! We disassemble the rear of the car to retrieve the module (1:16), then cut it open (9:25), remove the leaking battery (10:36), and show you how to clean the board (12:03) and replace the battery (16:18). Finally, we reinstall everything (20:00) and get it tested (23:20). This DIY is applicable to 2002-2008 B6 and B7 Audi A4 and S4 Avants (wagons), but its should be close enough to help out sedan owners as well. The module's part # is: 8L0 951 605A
Here is a list of the items we mentioned in the video:
Alarm module (8L0951605A) Cheaper than the dealer! amzn.to/3e7N71e
Battery amzn.to/30x1eIV (updated Amazon link 3/11/2021)
Torx screwdriver set amzn.to/3dZfrD0
De-soldering iron amzn.to/3bMRf5t
Soldering Iron amzn.to/2LKrXdz
Helping Hands amzn.to/3g3aFWV
Loctite PL Roof & Flashing Polyurethane Sealant amzn.to/3cMnymn
3M Adhesive Tape (6382) amzn.to/2LKrXdz
(As an Amazon Associate I earn from qualifying purchases made through the links above. Thanks!)
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[@luismiguelguerreiro]

Excellent demonstration of how to repair the alarm module. I wish you much success. Thank you very much.👍👍👍

[@willywinwin]

great fix its good to see somebody that can repair instead of replace and charge a fortune many thanks keep up the good work

[@cjshumate5035]

Thanks! This did the trick for my 2003 A4 with the alarm all my neighbors hated.

[@WooZie2007]

Hi all, i can confirm, on my jetta 2008 it works without internal battery, i just washed the motherboard with water and alcohol, after that a layer of lack protector and tested it, it works....i mounted it back, i checked with vcds and no fault error. Thank you very much🙏

[@KeirBriscoe]

great job. so nice to see someone who knows how to repair items instead of simply replacing.

[@thatlithornet6421]

Love it! You're extremely meticulous and informative!

[@DIYNexus]

Thanks! You missed your chance to say: "FIRST!" 😎

[@dbbyleo]

Great video! Ive got a 2011 Audi A3 TDI. The same thing has happened. I couldn't get two of the eight battery terminals off of the circuit board. The solder just would not melt. After googling a bit, it seems this can happen when the solder is corroded, so just a heads up for others. I cranked up my iron to over 800 degree F, and it just would not melt. I added flush, melted fresh solder on it but nothing worked. So for the negative side of the pigtails, I just had to solder the wire on top of the board. Also, for those with an A3, the alarm module is located in the front right wheel well, towards the cabin. You will also be dealing with a "shear bolt" to get the housing off, which will take some creativity to do. I hope to post a video, but for now, know that's what you'll be dealing with. I'm still waiting for the battery to come, so I don't know if I'll have success yet. Anyway, thanks for this great video! Awesome details and info and very well put together.

[@WindradeFarren]

I have to try this in a Q7! I kind of have the same problem, the alarm goes off randomly at night and dries the battery. I've checked the times where the alarm goes off and there's nothing that could possibly make it go off. Thanks for this helpful explanation, step by step. You are a genius!

[@alehhatsila5624]

Отличная работа. Спасибо за информацию.

[@markmosher1856]

Really helpful video. Unfortunately both A4s that I bought had completely inoperative alarm horns (not a peep from them ever). I tried cutting them open and cleaning them up and connecting a 7.2 V battery but they would not sound when the alarm activated. I still made use of this video by purchasing a junk yard sourced alarm horn and proactively replaced the battery so the replacement horn would last a while. That approach has worked well on the first car which has been running for a year and a half since it was put on the road. The second car is still a work in progress but I plan on treating that alarm horn the same way .I like the idea of getting that battery out of the alarm horn in any event. Those horns are too expensive to be replacing periodically. This way I can just replace the battery.

[@robturner4514]

Great video. My old 2002 VW Passat has the same problem so I'll look at the siren. Thanks again.

[@juvenitto]

Well done and simple explained, unfortunately i did never soldering anything in my life:D

[@willywinwin]

very well explained great demo do some more please

[@layddly]

Keep up the great work. Very informative.

[@DIYNexus]

Much appreciated, more to come!

[@johngonda6447]

Well done!

[@adamgosney8069]

Excellent video thanks 👍

[@rcabert70]

Very helpful!

[@KeirBriscoe]

Doing the same repair to my car right now. My board was not as corroded as yours so I have hope this will work. So far the hardest part is sourcing a battery. Here in Canada things are generally less available, or way too expensive.

[@Infinitpossibilities]

See my comment above. They deliver internationally. Not sure of the cost though

[@KeirBriscoe]

@@Infinitpossibilities Got a battery with the correct specs, however my horn did not revive. I ended buying a used on on ebay, now im contemplating doing the upgrage to prevent the issue...

[@lee20021242]

Wow i will do it ! Thanx i dont think about the battery of siren

[@jasondean3332]

I know this is so random but I’m in a rabbit hole and I think you might be able to help. Did you ever figure out how to take the flanges off that Craftsman 115 7398 bench grinder??? I’m stuck on mine right now. Hahahaha. I hope you’re the dude I’m looking for. Thanx

[@DIYNexus]

I don't think I'm 'The Dude", but I appreciate the message nonetheless. I actually have an old grinder I want to do a resto on, but haven't posted about it in years. Maybe on Garagejournal.com? Either way, thanks for watching!

[@sexyparty478]

Could I just remove the connector and install the battery directly to the board?

[@osh6767]

About to do this on my car mine was cooked so bad and broke the housing thinking it came apart. Got a junkyard replacement and a battery from link you posted. How’s yours holding up?

[@petewilliams5517]

Hi could you tell me are these sirens all the same audi vw ect my car is B6 passat estate 2005-2010 mine doesn't make noise at all but all indicators flash only so need to swap hence why I'm asking are all these sirens compatible to all vw audi seat ect many thanks and a great video I may go the same route as your video shows thanks 👍👍

[@DIYNexus]

Many are similar, but not all. Check that your part number matches the replacement. If you want to take a little more risk, check the pins in the connector vs. the replacement. I know that some that look the same have fewer pins (and therefore won't work).

[@fivedotsdave9723]

It's not difficult to see why that car is leaking when you take a look at the very shoddy bodywork repair where the alarm module was located.....

[@josegirao1229]

Hello I have an A4 8e from 2002 and the door's led light was always on (fixed) what can it be? Thanks! Hug

[@chipmeat]

Excellent video, but can I ask did the batteries start charging after the fix? Thanks

[@DIYNexus]

Great question! I wasn't able to verify charging while I had everything apart. It worked well for months, but the car has been sitting again and I think the battery is flat. I need to disassemble the trunk area and test it. I'll message back when I check.

[@chipmeat]

@@DIYNexus Great! on doing this fix for my mk1 tt seems to be in the same state as yours so hopefully it may be saved only problem is I can only find a 7.2v 400mah here in the uk so I hope the extra 100mah will not be a problem

[@gavbrown164]

I’ve got an s3 8p 2007 ware is my siren located

[@thisisayoutubechannel4752]

This is a really nice idea! I have an ultrasport as well and I have gone through 2 modules now. I like the idea of having an external battery. I keep my car in storage in the winter so it may be a good idea to disconnect that battery while in storage. Do you have a link to the pigtail that you soldered to the board?

[@DIYNexus]

Thank for the compliments! I looked everywhere for a link to a matching connector, but couldn't find any. I even updated my Amazon link to a cheaper available battery that should work perfectly. If you're handy enough with a soldering iron, I'd suggest just pulling a connector set off of a piece of scrap electronics and replacing the battery end. I'll post back if I find the correct connector though!

[@josegirao1229]

By the way, what is the name of the electronic part that you stuck outside the alarm?

[@Spartan_82]

Is it located on the same spot on a A6 2007? Thanks

[@danielslaughter104]

How has the battery held up over time? You've got me confident enough to try this out, I have the battery in my cart on Amazon already lol.

[@DIYNexus]

The battery has held up well, but it seems my siren module 'may' have a parasitic drain. I still haven't finished the car yet though, so I'm hoping I catch it soon. Give the diy a try! 😀

[@Spartan_82]

Is the alarm in the same place in a A6? Thanks

[@user-it5pn6mj5r]

Great video i have audi a8 d3 2009 (same alarm siren ) and i have a problem with the alarm, as soon as i connect the vehicle's battery the alarm starts working and the key does not turn it off. The batteries of the alarm are not good (as in the video) could this be my problem?

[@DIYNexus]

Absolutely. If there's a short in the siren module, it could go off and not allow it to be silenced. If you have access to VCDS or a similar scan tool, check for codes and the "reason" the alarm is going off. That may help.

[@user-it5pn6mj5r]

Thank you

[@estebanortiz528]

hello. Did you solve the oil pressure problem? I have the oil pressure light on, I have changed the sensor and I have tested the pump and it is still the same. Do you have any idea what it could be?

[@DIYNexus]

Yes, kinda. Oil pressure issues on the 3.0L are often related to oil quality and brand, filter quality (OEM ONLY) and the small check valve in the top of the engine. We ran some Seafoam and fresh oil through it and it seemed to take care of the problem (for now). If that doesn't help, consider replacing the check valve, and then move on to replacing the connecting rod bearings. Good luck!

[@wafi3187]

I have a exact module that actually works I got it as a replacement for my older type module, if I just cuz the battery off would that cause trouble?

[@DIYNexus]

I'm not actually sure. I don't think there would be an issue electrically, but it may store a code in the computer for a failed/missing battery.

[@wafi3187]

@@DIYNexus I just cut mine off lol I’ll see how it goes my car is 03 and the one I had in car is completely gone no way to repair, but the new one I got from 05 car still worked and cracked open and saw the battery already starting to leak acid so I cut the bars holding the battery on with blades hopefully it didn’t damage the motherboard

[@Devorigami]

@@wafi3187 Did it work after you cut the battery off? Or did you have to replace the battery?

[@wafi3187]

@@Devorigami The reason I cut the battery of is so it won’t ruin the mother board when it leaks, you can replace the battery with RC battery if you hood with electronics, it will world absolutely fine without battery mine works perfectly

[@kaiboso8605]

Will it work without battery?

[@DIYNexus]

Excellent question! I never tried it. If anyone has experience with this, please comment!

[@Spartan_82]

Can you simply disconnect the module?

[@DIYNexus]

Yes, but you'll lose the siren and the arm 'chirp' noise. It also may set a DTC in one of the modules.

[@stormtrooper2k581]

does the mAh of the replacement battery matter?

[@DIYNexus]

Yes, but it really only needs to match or reasonably exceed the original mAh. Higher is generally ok, but you end up with a size issue if you go to high.

[@CraigMansfield]

My lights keep flashing. It's annoying me to death. I just want to deactivate it, it's useless anyway.