Alarm Randomly Going Off + Other Weird Electrical Issues

[SJorge3442]

Two times tonight I was told by other people that my car lights were on. First time I walked out of the gym to check and my was just sitting there with no lights on. Second time my neighbor knocked on my door 15ish minutes after I got home from the gym and said my lights were going off and on but had stopped. After hitting unlock, my alarm lights started flashing (I dont have a siren any more due to the dead battery) Whats up with that. My car has NEVER initiated the alarm EVER in my 6 years of ownership.

I've also been having another issue when the car is at idle I have a slight rpm surge which is causing my fogs/dash/radio/interior lights to dim a little. Battery charging around 13.6ish which is where it usually charges on my car (both with my old alternator and my current one).

Are these two related maybe? Is there a module going bad? What module operates the alarm? I feel like I've been lucky with ghost chase issues with this car but this one has me stumped and perplexed right now. Its a 3.0 for what its worth, but I dont think that matters too much here.

[RDA990]

I had the alarm going off randomly a few months ago, it turned out to be the hood latch switch. The thin wires that come out of the switch were already falling apart and when it rained water would get in those areas and cause a short. The alarm thought someone opened the hood so it would go off.

You could also use VAGCOM and the alarm module to see what triggered the alarm IIRC.

[krew53]

The random alarm going off and headlight flash can come from dead alarm siren battery. You will need to pull it and replace it otherwise it will continue to happen. There is some threads on this if you search.

The alarm siren is in the trunk on the right side behind the panel.

[SJorge3442]

I had the alarm going off randomly a few months ago, it turned out to be the hood latch switch. The thin wires that come out of the switch were already falling apart and when it rained water would get in those areas and cause a short. The alarm thought someone opened the hood so it would go off.

You could also use VAGCOM and the alarm module to see what triggered the alarm IIRC.

Might have to finally get a ross-tech cable. Not sure how I've made it 6 years without one . When that was happening with your hood, would the dash show the hood as being open?

The random alarm going off and headlight flash can come from dead alarm siren battery. You will need to pull it and replace it otherwise it will continue to happen. There is some threads on this if you search.

The alarm siren is in the trunk on the right side behind the panel.

I thought this too, but I dont have the siren module anymore. I had removed that about 3 years ago due to the bad batteries and didnt care enough to wire up near batteries.

[IndoReef]

2nd on the hood latch, one night my alarm did the same thing, randomly going off constantly.
It was the hood latch shorting out, i just cut the two wires, problem solved.
Car can't tell now if the hood is open or not, shows closed

[Tahoe3.0]

x3 for possible hood latch. Had same exact problem indo and rda experienced

[MetalMan]

Had same issue with my old B5. I can't recall what was triggering it, but unplugging the hood latch switch ended the problem (regardless of whether or not hood latch switch was the problem).

[RDA990]

Might have to finally get a ross-tech cable. Not sure how I've made it 6 years without one . When that was happening with your hood, would the dash show the hood as being open?

Even the eBay ones are better than nothing. I honestly don't remember if the dash showed the hood was opened WHEN the alarm went off, but it was around the time I was having the dash show the hood was opening/closing while driving.

It was the hood latch shorting out, i just cut the two wires, problem solved.
Car can't tell now if the hood is open or not, shows closed

I can't recall what was triggering it, but unplugging the hood latch switch ended the problem

If you ever let the oil light come on you'll have a problem with it going away. The car wants the hood to physically open before it checks the oil levels again. The way it knows the hood was opened is with the hood latch switch. You'll have to short the wires for it to know you "opened" the hood and eventually recheck the oil levels to turn the light off.

[IndoReef]

If you ever let the oil light come on you'll have a problem with it going away. The car wants the hood to physically open before it checks the oil levels again. The way it knows the hood was opened is with the hood latch switch. You'll have to short the wires for it to know you "opened" the hood and eventually recheck the oil levels to turn the light off.

I actually had it come on last year, just resolved the oil issue and light went away after a few days of driving.

[Spike00513]

If you buy a ross-tech cable, you can sell it for near what you paid, if you move on from the car.
When folks maintain a used car to avoid new car payments of $300/mo+, I don't know if the VCDS one-time purchase price is so extreme.

similar thing happened to me; I removed the alarm siren because it kept going off. Might've melted the circuitboard with bad batteries, and a replacement alarm siren list price was expensive.
but the door red LED kept flashing fast, which I hear is what the B6 does if it detects a problem. So maybe the siren going off was not the problem itself, but a symptom of one.

I wondered if it was a door latch microswitch because I heard Jetta's do that (similar car) and I think people have better luck on them replacing the whole door lock module thing instead of tearing it apart to access the small individual microswitches. Also expensive.
But I don't remember if I scanned into the car to try and see what would have triggered it. Because if it was a hood latch instead, that sounds like an easier fix than a door.

Even the eBay ones are better than nothing. I honestly don't remember if the dash showed the hood was opened WHEN the alarm went off, but it was around the time I was having the dash show the hood was opening/closing while driving.





If you ever let the oil light come on you'll have a problem with it going away. The car wants the hood to physically open before it checks the oil levels again. The way it knows the hood was opened is with the hood latch switch. You'll have to short the wires for it to know you "opened" the hood and eventually recheck the oil levels to turn the light off.

I think I've seen it happen once on a B8. I believe they use an oil level sensor that displays a reading in the instrument cluster, that requires the hood be open to check. Well, this was not working; turns out the hood switch appeared to be not functioning; this was temporarily fixed by inserting a paper clip into the terminal pins to trick it into thinking the hood was open, so that it would display the oil level

[krew53]

That's why I mentioned the alarm siren. I was having the headlight flash issues still after removing the unit AND the fuse. Think that it can still cause issue with CCM causing the headlight and door alarm light to wig out. Bought one off a junkyard and replaced and have not seen the issue in years.

The RPM surge and electronics freaking could also be the CCM. I would try and fix the siren before moving to the CCM.

[SJorge3442]

I've opened and closed all doors/trunks/hood since the initial post and no one has mentioned to me that they've seen my lights going off since. Obviously that doesn't mean its not happening, but a good sign. I am planning on pulling up my carpet today to take a peek at the CCM as Ive had a parasitic draw since owning the car and when I did a fuse test, it was pointing to the CCM. I think the siren/alarm issue is solved for now, now time to figure out the other electrical issues. The surge is almost like a breathing pulse where my lights dim and get bright, so its totally noticeable while driving around town, especially since I have my fogs and parking lights coded for RoW and they're always on. I just don't want this to turn into a larger issue and leave me stranded somewhere or worse, left without lights.

[SJorge3442]

Pulled the ccm. Looks perfect....

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[yanni6556]

I am also chasing some electrical gremlins and i was told by a qualified electrician to look into grounds. If for example a ground is bad in one section of the car it can spike to another usually to a module and cause lots of weird things to happen. Unfortunately its kind of hard to source where all the grounds are in the car so we are left to manually look.

[Spike00513]

I am also chasing some electrical gremlins and i was told by a qualified electrician to look into grounds. If for example a ground is bad in one section of the car it can spike to another usually to a module and cause lots of weird things to happen. Unfortunately its kind of hard to source where all the grounds are in the car so we are left to manually look.

wouldn't an EWD (Electrical Wiring Diagram) of the car tell you all the ground locations?

[SJorge3442]

Alright so the alarm hasn't been an issue, but my surge at idle is still there.

Could resistance in my positive battery cable cause this? I've had issues with my hot terminal getting corroded before but it's not corroded recently. It has me thinking the cable itself could old and built up with corrosion?

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[RDA990]

I actually had it come on last year, just resolved the oil issue and light went away after a few days of driving.

You're right. Looks like my hood wiring is bad again so the light stayed on and went off on the 2nd or 3rd day.

[JUSADUB]

I have this problem sometimes. I thought it was the factory siren. I took it and out and still does it. ill have to check the hood latch.

[oaybar007]

Ah the good old hood latch switch. Mine shorted out years ago in cold weather and my alarm kept going off all night. I just cut the wires too.

[JUSADUB]

so i unplugged the switch to the hood latch. the alarm is still going off along with the lights. I took out the siren out of my avant awhile and never put it back since I had my avant parked for 6 months.

[DPDISXR4Ti]

so i unplugged the switch to the hood latch. the alarm is still going off along with the lights.

It could be an issue with the lock and/or CCM. When I only had a plastic valet key for a short time I was very gentle when unlocking the door. I think what I found is that I could unlock the door but not activate the electronic switch to trigger the CCM. As a result, the CCM thought I had broken into the car and was stealing it. I had this happen twice in cold weather only when using the physical key to unlock the door, so I can't be certain of what I've said here - it's just a semi-educated hunch.

[JUSADUB]

It could be an issue with the lock and/or CCM. When I only had a plastic valet key for a short time I was very gentle when unlocking the door. I think what I found is that I could unlock the door but not activate the electronic switch to trigger the CCM. As a result, the CCM thought I had broken into the car and was stealing it. I had this happen twice in cold weather only when using the physical key to unlock the door, so I can't be certain of what I've said here - it's just a semi-educated hunch.

The CCM looks good. Its dry but the carpet is wet, Im going to let it dry out tonight and see if i spot where the water is coming from.

[SJorge3442]

The CCM looks good. Its dry but the carpet is wet, Im going to let it dry out tonight and see if i spot where the water is coming from.

Yeah my CCM looks find too and my carpet didn show any signs of moisture. I really don't know what to do at this point with my 3.0. The idle surge im having seems to come and go and at this point I'm loosing my wits over it. I might pop off the injectors and clean them today to see if I can get any progress on the surge. The alarm is the least of my worries.

For what CCM's go for on ebay. You and I are probably better off just snagging one and swapping them out to see what it does.

[JUSADUB]

Yeah my CCM looks find too and my carpet didn show any signs of moisture. I really don't know what to do at this point with my 3.0. The idle surge im having seems to come and go and at this point I'm loosing my wits over it. I might pop off the injectors and clean them today to see if I can get any progress on the surge. The alarm is the least of my worries.

For what CCM's go for on ebay. You and I are probably better off just snagging one and swapping them out to see what it does.

Just checked under the cowling. The cover for my ECM is broken on the back corner. I believe the water is dropping into the car by the fuse panel from it. Im gonna go to a few wrecking yards to find one and maybe a used siren too.

[SJorge3442]

Just checked under the cowling. The cover for my ECM is broken on the back corner. I believe the water is dropping into the car by the fuse panel from it. Im gonna go to a few wrecking yards to find one and maybe a used siren too.

Hmm. Maybe I should check too. I'm swinging by Napa for a fuel filter today and was planning on slapping that in quick since it's such a low effort job.

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[JUSADUB]

Hmm. Maybe I should check too. I'm swinging by Napa for a fuel filter today and was planning on slapping that in quick since it's such a low effort job.

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Looks like i fixed mine. Ran vagcom and it came back with open circuit on the rear glass sensor. I unplugged it and its not going off. Looks like the wire was pinched when the hatch trim was installed at some point.

[JUSADUB]

Any updates on yours?

[SJorge3442]

Any updates on yours?

Negative. Swapped the fuel filter with no change. I had a strange PCV symptom last week that got me thinking I might have a crankcase breather problem/clog. While idling I was getting a whirling noise from the engine. If I loosened the oil cap, it got better. I wasn't able to check my lights at the same time, but I'm still dealing with the strange idle surge of my parking lights/interior lights. I have noticed that after a hard run, its less likely to occur (it doesn't happen all the time), but it's still there.

The next step is checking the crankcase breather system for gook and that fun stuff. If that doesn't work, clean/reman injectors are next on my list. This is really starting to drive me crazy, but being in the northeast without a garage makes diagnosis difficult this time of year. Not to mention I don't want to go touching engine bay stuff when its cold out for fear of stuff breaking.

[SJorge3442]

Finally had some time to mess with this. So i think my alarm issues are linked to a bunch of intermittent issues with door locks/ trunk sensor/ and hood sensor. W/e thats the least of my worries.

Now to the fun stuff. The idle surge had started becoming a 80% of the time sort of issue. Sometimes it was surging, sometimes it was good. I finally got a ross tech cable (i know i know) 6 years after getting my a4. Anyway, I hopped into the adaptation channel and added a few revs to my idle and the problem is done and now my battery voltage is much steadier than it was ever before. Holding a solid 13+ without dropping below that now. At my old idle (740) it would bounce from 11.8-13.6 ish per VCDS. I might try bringing the idle down slightly so its not at 800rpm on the money, but damn does the car feel good at idle now. Nice and smooth and less "chunky" sounding. My 3.0 always seemed like it was plugged up somewhere at idle in the 70k miles and 6 years I've owned it and now it sounds great.

Anyway, while this isn't a true fix for this problem I was at least able to straighten it out for the time being.