Nuisance alarms

[1999 996C4]

Hi

I'm a new owner of a 99 C4 and have been experiencing nuisance alarms. The car can be sitting in the driveway for 24 hrs plus when for no apparent reason the alarm goes off. Unlocking and re-locking shuts it off (of course). I usually get no beeps when locking, sometimes 1 but never 2. Any suggestions anyone? Is there any way to shut the alarm off?

Thanks

Ross

[Loren]

:welcome:

Best solution would be to use Durametric software, a Porsche PST2, or Porsche PIWIS tester to read the alarm fault(s).

Those faults will pinpoint what zone is causing the problem. Maybe as simple as replacing one sensor or switch.

[1999 996C4]

Hi Loren et al

Thanks for the welcome and the advice.

Just got back from the cottage - left the key with the neighbor and he disarmed it 3 times - popularity on the street is waning quickly. Anyway, I rebooted by disconnecting & reconnecting the battery - fingers crossed. Meanwhile, I gather that most owners who are mechanically inclined have 1 of the diagnostic tools mentioned above and it seems the only affordable one is the first so I think I'll order it - any advice to the contrary?

Ross

PS these are amazing cars, aren't they!

[1999 996C4]

Fyi - that didn't work and now, using the brute force and ignorance approach, I disconnected the battery. ​I am a bit perplexed by the time delay though - wouldn't a sensor/switch input trigger it immediately?

I also found something interesting in another thread "Until you find the issue, lock the car then unlock the car and the car will automatically lock itself after 30sec or so as long as you do not open the door... that way you can have the car locked at work without the alarm going off.."

I will test that theory tomorrow, not that it solves the problem

[Richard Hamilton]

As Loren says, getting a proper diagnostic check will show what is causing the alarm to go off.

However, random false alarms like this are sometimes caused by a faulty interior monitoring sensor. If you double-lock the car (two presses of the button, or two turns of the key) it will disable the interior monitoring. It might be worth a try.

Also, if you have the optional tilt sensor and siren, the tilt sensor can often fill with water. On the early 996's, these were fitted to the right hand side of the battery (as you look at it). The sensor has a clear casing, so you can see if it has water in it.

(Photo courtesy of Tool Pants)

[1999 996C4]

Thanks Richard - but no tilt sensor. I had already tried the double click and it beeped once and the alarm went off later. It seems like a deteriorating condition of some sort, as the intervals between alarms are getting shorter. Anyway I ordered the Durametric today so I should have an answer in a week or so - hopefully a cheap one.

Meanwhile. I'm still open to suggestions

[logray]

The durametric should be able to pinpoint the fault codes where the problem is sourcing from which could be ... (in no particular order, and not complete list)

alarm unit itself

fuel door flap

passenger comp. monitor

microswitches for doors

front hood latch

rear engine bay latch

radio ground

oddments tray switch

"other"

It's an exercise in futility and expensive if you try to "fix" all of the above possibilities without first knowing where the faults are coming from.

[Karl996]

Ross

Welcome from one newbie to another facing the same problems.

I'll share my findings so far although most of it has been covered.

For Durametric download the V6 software. I believe this is the only version which will let you clear alarm codes. You can then see what is triggering the alarm the next time it goes.

When you lock normally, you should have NO beeps at all IF everything is armed properly. A beep means something is not closed, latched etc properly.

Like you I am slowly loosing popularity with the neighbours so my solution is to lock, then unlock and walk away. The car will lock itself in about a minute (think it waits 20secs to make sure and then 30secs later it will lock).

Right now I'm at the stage of having reset everything and awaiting it to trigger again so I can read the codes.

By the way do you have an after market stereo or the stock one ?

Good luck and do post back if you find the problem.

Karl

[1999 996C4]

Thanks Karl

Nice to know I'm not alone - but you're a bit too far away to get together for a beer.

I'm surprised that the Durametric didn't find your problem right away - were there too many events to analyze?

I did the lock-unlock manouvre last night and the alarm went off 4 or 5 hrs later! I thought this disarmed it but apparently not in my case. Could this be a clue?

Also, when I double click to disarm the interior sensor it always beeps - is this an indication of something do you think?.

The car came with a really good aftermarket stereo - 2 separate amps with 800W+ A bit of a waste because I prefer to listen to the engine. Are you thinking about the grounding or insulating of the security wire from the original?

Good luck with your issue

Ross

[RFM]

Don't forget the build-in battery in the siren, when the battery is defective, there will be no error code generated.

[Karl996]

Ross

We'll have a virtual beer when we get this fixed !!

Re Durametric - yes I had to many events recorded to even know where to start. HEnce the clearing of all codes and a reassessment.

On the locking the car without activating the alarm try this. Press the button on the remote once (this should lock and on my car the lights flash twice) wait for the lights to finish flashing and then press once to unlock (Again on my car the lights flash once and the interior light comes on). Now wait. After about 20secs the interior light goes off and about another 30 secs later the car self locks. Voila !! No alarm.

There is a lot of documentation on aftermarket stereos being one of the reasons why the alarm does not initiate properly. In summary it's about a contact between the stereo and the frame holding the stereo. Most stereo shops will not insulate this wire causing the alarm module to think that the stereo has been pulled out.

[Karl996]

Don't forget the build-in battery in the siren, when the battery is defective, there will be no error code generated.

If the battery was low would it cause the alarm to go off randomly ?? And any pictures on where this battery can be found.

Thanks in advance

[RFM]

The siren and the battery are build as one piece and not separable, and yes, the alarm go off randomly.

[logray]

As RFM points out, IIRC on rest of world models the siren is driven by a separate battery. There was a thread recently where I learned that.

If I'm not mistaken on USA cars it is driven off the main battery, under the front trunk center cowl.

[1999 996C4]

Hello All

What I seem to have is no siren, just a horn beside the main battery - it's a US spec car imported to Canada.

Interestingly, the alarm has not gone off for a couple of days now and I'm beginning to think that the problem is simply a main battery which is not in such good condition and it's voltage is dropping below some threshold, particularly in the early (2AM) morning, and the alarm module triggers on undervoltage. I read something somewhere about this being possibility if the voltage goes below 12V or so. I have been driving more and the overnight temp's are rising which tend to keep voltage up. Crazy? maybe. When I get that durametric thing we'll find out.

Ps some f! idiot put a small crease in the front bumper while I was parked today - no paint damage - any ideas on how to remove using heat or ?

[Karl996]

I think I am now going to beat my head on the wall.

After having all the codes cleared, the alarm has gone off 3 times when I lock it the correct way with NO codes registered.

I'm at a loss as to what to do.

I did notice that when a neighbour alarms their car my alarm goes off a couple of seconds later. This happened once. Coincidence ??

I'm thinking:

1. Check to see if my siren has a battery (ROW car)

2. Lurk in the carpark to see if it is my neighbours car

3. Give up

Please help if you can think of any other suggestions.

Ross - sorry to hear about the bumper. Very painful I know. I was managed to get a dent out from a bumper by pouring hot water on it and pressing it out. Or try a heat gun but make sure you don't melt the top coat or paint.

[logray]

Since your car is a ROW car it may have a tilt sensor, which is picking up the ground vibrations?

I did notice that when a neighbour alarms their car my alarm goes off a couple of seconds later. This happened once. Coincidence ??

[logray]

Crazy? maybe

Not really! A low battery can cause all sorts of untold strangeness on any car.

To eliminate this possibility remove the battery and take it to a qualitfied auto parts store and they can test it for free. Replacement costs of a battery are in the $75-100 range, so in that case, my opinion is that your sanity is more important than $100, if the battery is suspect.

[1999 996C4]

to Karl996

When you say no codes registered do you mean fault codes? If so I think this means that the control module is functioning correctly. However, whatever is triggering the alarm should be stored in the Event memory which stores the 10 most recent inputs to trigger the alarm. Can you retrieve this log with your Durametric software?

re undervoltage theory: apparently this only triggers the alarm at 8.5 volts so if this is true the battery needs to be toast. However I may get a new battery anyway & put the old one in the boat

BTW - did you know you can get a complete shop manual CD on ebay for cheap? Probably some copyright issues so don't take this as a recommendation

[1999 996C4]

Update on alarms: I was just informed by the neighbor across the street that the alarm went off twice last night - apparently my wife and I are getting used to it but the neighbors not so much. Battery now disconnected for the night.

[Karl996]

Crazy? maybe

Not really! A low battery can cause all sorts of untold strangeness on any car.

To eliminate this possibility remove the battery and take it to a qualitfied auto parts store and they can test it for free. Replacement costs of a battery are in the $75-100 range, so in that case, my opinion is that your sanity is more important than $100, if the battery is suspect.

Logray - Thanks for the input. Battery and tilt sensor (if I have one) will be next on my list. Interestingly the voltage reading whilst running with the aircon is 12.8 to 12.9V.

to Karl996

When you say no codes registered do you mean fault codes? If so I think this means that the control module is functioning correctly. However, whatever is triggering the alarm should be stored in the Event memory which stores the 10 most recent inputs to trigger the alarm. Can you retrieve this log with your Durametric software?

re undervoltage theory: apparently this only triggers the alarm at 8.5 volts so if this is true the battery needs to be toast. However I may get a new battery anyway & put the old one in the boat

BTW - did you know you can get a complete shop manual CD on ebay for cheap? Probably some copyright issues so don't take this as a recommendation

Ross - No fault codes registered in Durametric. I guess the next step is battery/alternator as mentioned above. Too bad I dont have a boat to put the old one in !!

I have the workshop manuals in pdf. Think i searched somewhere and managed to download them.

By the way, apologies for hijacking your thread. Just thought since we were facing similar problems I would add on to it. Hope you don't mind.

[logray]

Update on alarms: I was just informed by the neighbor across the street that the alarm went off twice last night - apparently my wife and I are getting used to it but the neighbors not so much. Battery now disconnected for the night.

You could remove your horn fuse temporarily until the problem is fixed..

[1999 996C4]

thanks logray - I thought this would guarantee that the alarm would trigger (albeit quietly) due to the module detecting an open circuit . Is this not the case? If so would it only happen once and immediately? I don't know how long the alarm goes before shutting itself off - and I'm afraid to ask the neighbors.

Hi Karl996

If I understand correctly the module stores an event code whenever the alarm goes off which tells you which sensor tripped it, which is different from the fault codes. I would hope that the Durametric can read this and point you towards the culprit. This is what Loren was saying back in post #2

[logray]

Without a fuse, the horns will not sound, yes the alarm can still trip. However perhaps a more sensible way to buy some time to troubleshoot and keep the neighbors happy rather than continually disconnecting/reconnecting the battery.

Edited April 13, 2012 by logray

[Karl996]

A quick update. Didn't get as much done as I would have liked this weekend.

I have ascertained that I do have a tilt sensor and it does not appear to be water logged.

I've decided to pursue the line of reasoning in Logray's Strange Low Voltage Problems post. My problems and observations appear to be identical and I feel there is no point pursuing the random alarms until I am confident the electrical/charge system etc is functioning 100%.