Truth Posted January 9, 2022 Report Share Posted January 9, 2022 Hi All ! Happy New Year A couple of weeks ago the alarm went off in the middle of the night for no reason! It didn't happen again and then last night I put the alarm on, walked away and it went off again. I read some where that this could happen if the battery was going in the fob? Changed the battery on the fob today (the red light was still activating on the fob before changing it) and now I can't get it to work at all with the old or new battery in, no ted light, nothing! I was very careful when I changed the battery so surely I've not damaged it and I'm totally confused as to whats happened? Any ideas folks? Cheers Quote Link to comment Share on other sites More sharing options...
½cwt Posted January 9, 2022 Report Share Posted January 9, 2022 Not the fob battery, the main battery can be a cause of false alarms due to a drop in voltage being a trigger for the alarm. 986 and 996 alarms are a whole minefield once they start misbehaving, have you tried just putting the battery in the fob upside down to discharge the circuit and the refit it correctly? This link to JMG Porsche is the most thorough independent examination of these alarm systems, hope it helps: JMG Porsche - Independent Porsche Specialists - Porsche 996 and 986 Boxster Alarm primer 1 Quote Link to comment Share on other sites More sharing options...
Truth Posted January 9, 2022 Author Report Share Posted January 9, 2022 Cheers mate. I had read about the car battery drop in voltage can cause the alarm to go off but 100% read it can be down to the battery in the fob causing in......... that I couldn't understand! Now I've done what you suggested (put the battery in backeards and then the right way) and now the red light on the fob is working again (its flashing when I press the button) BUT its not actually switching the alarm on ond off on the car still 😡😡 Any more tips to get that sorted......... 😉 Quote Link to comment Share on other sites More sharing options...
Boxob Posted January 9, 2022 Report Share Posted January 9, 2022 (edited) It's not just the condition of the main battery that can trigger an alarm. The siren has its own rechargeable battery. With age that battery, which draws from the main battery, does not hold its charge as it used to. When it drops the alarm system 'thinks' it's being interferred with so triggers. Not heard of the fob battery causing a trigger. Edited January 9, 2022 by Boxob Quote Link to comment Share on other sites More sharing options...
Truth Posted January 9, 2022 Author Report Share Posted January 9, 2022 Well its in for a full servive in February so I'll get them to take a look at the battery(s) then 👍 I just wished I hadn't messed changing the fob battery now and screwed that up 😡😡 Quote Link to comment Share on other sites More sharing options...
½cwt Posted January 9, 2022 Report Share Posted January 9, 2022 Have you tried the repairing operation of turning the key anti clockwise and holding the door button at the same time. I think it is procedure is covered in the JMG document I linked to. I had similar issues with one of my keys and then managed to put the working spare through the wash... Ended up getting a new key head and programming from my local Porsche Centre, cost about £250, not had a problem since. When budget allows I'll get the second key fully working again too rather than just having a dumb back up. Quote Link to comment Share on other sites More sharing options...
Truth Posted January 9, 2022 Author Report Share Posted January 9, 2022 Tried it mate, no good 🙁 Quote Link to comment Share on other sites More sharing options...
Paul P Posted January 9, 2022 Report Share Posted January 9, 2022 Have you checked for any signs in water or dampness in the carpet or the foam under the passenger seat ? That’s the alarm control unit under there…. also. Have you checked the car battery state, if the siren backup Battery has gone then it will constantly be trying to recharge itself from the car battery and will drain it over time. Quote Link to comment Share on other sites More sharing options...
charlieboy2608 Posted January 10, 2022 Report Share Posted January 10, 2022 Good points by Paul P above....and not to be the bearer of possible other issues but did i read on here that a key has a limited number of uses before it just stops working? Do you have a spare key to try?? Quote Link to comment Share on other sites More sharing options...
½cwt Posted January 10, 2022 Report Share Posted January 10, 2022 19 minutes ago, charlieboy2608 said: Good points by Paul P above....and not to be the bearer of possible other issues but did i read on here that a key has a limited number of uses before it just stops working? Do you have a spare key to try?? The limited number of uses is covered in the JMG Porsche article linked above. Quote Link to comment Share on other sites More sharing options...
Truth Posted January 10, 2022 Author Report Share Posted January 10, 2022 Hi Paul No water ingress and I am useless so wouldn't know how to check battery life! Its in for a service in a few weeks so will ask them to take a look. Hi Charlie, I was aware of that but this keys only two years old. The old key is working fine 👍 Quote Link to comment Share on other sites More sharing options...
K.I.T.T. Posted January 10, 2022 Report Share Posted January 10, 2022 On 1/9/2022 at 11:01 AM, Truth said: I read some where that this could happen if the battery was going in the fob? This is not correct. The key only transmits when you press the button. It can't randomly trigger the alarm due to a low battery. 1 hour ago, charlieboy2608 said: i read on here that a key has a limited number of uses before it just stops working? Haven't heard of this either. A few of us with 986s approaching or past 150k miles on the original fobs. Water ingress as suggested, but this doesn't seem to be an issue. Weak / dying battery as previously mentioned would be my next guess. Its one of those situations where having access to Durametric would be useful - it will actually tell you what caused the alarm to trigger the last X occasions. Quote Link to comment Share on other sites More sharing options...
Paul P Posted January 10, 2022 Report Share Posted January 10, 2022 40 minutes ago, Truth said: Hi Paul No water ingress and I am useless so wouldn't know how to check battery life! Its in for a service in a few weeks so will ask them to take a look. Hi Charlie, I was aware of that but this keys only two years old. The old key is working fine 👍 If all is good with your other key, then as long as the car is behaving itself ( can lock/unlock, start the car ) then unlikely any issue with the car battery. seems to be that one keyfob - you may need to get that looked at as part of the service - or perhaps consider sending to the key fob repair outfit that is mentioned on here often ( struggling to remember their name ). Think the original alarm triggering may be linked to the siren - so 2 issues, hope they can help at the service. Quote Link to comment Share on other sites More sharing options...
Truth Posted January 10, 2022 Author Report Share Posted January 10, 2022 Thanks all, it must be the battery by the sounds of things which really hacks me off as both bloody keys worked before I changed the battery 😡😡 . Thats cost me 🤔🤔 Quote Link to comment Share on other sites More sharing options...
charlieboy2608 Posted January 10, 2022 Report Share Posted January 10, 2022 22 minutes ago, K.I.T.T. said: Haven't heard of this either. A few of us with 986s approaching or past 150k miles on the original fobs. From what I remember reading on this forum it was not mileage related. I believe it was activation count that caused a non performing key. Quote Link to comment Share on other sites More sharing options...
K.I.T.T. Posted January 10, 2022 Report Share Posted January 10, 2022 Am not suggesting it is mileage related, but I am suggesting cars with higher miles, thus used regularly, are likely to have had their key fobs used (significantly) more than garage queens. Do you have any further info about keys having a limited number of uses and what this actually is? Have been using the same remote key on my VW for the last 14+ years and struggle to see why / how this would be different for another manufacturer. These keys are relatively simple transmitters. There is the potential that if you have a duff key with an intermittently stuck button - or - you the button is somehow pressed (a lot) when not in the vicinity of the car, they become "out of sync" as they use rolling codes. Either way, why the OP's alarm is going off is nothing to do with the key. Quote Link to comment Share on other sites More sharing options...
Paul P Posted January 10, 2022 Report Share Posted January 10, 2022 11 minutes ago, K.I.T.T. said: Do you have any further info about keys having a limited number of uses and what this actually is? It's covered in this write up by @Indi9xx https://www.jmgporsche.co.uk/item/234-996-986-alarm-primer I think the issue is the system in the 9x6 reaches the end of the available codes "list", and doesn't roll over and start again - so a finite number of operations before the end of the available range is reached - but I may be over simplifying. 1 Quote Link to comment Share on other sites More sharing options...
Truth Posted January 10, 2022 Author Report Share Posted January 10, 2022 I'm nowhere near that in 2 years 🤣 Quote Link to comment Share on other sites More sharing options...
½cwt Posted January 10, 2022 Report Share Posted January 10, 2022 24 minutes ago, K.I.T.T. said: Am not suggesting it is mileage related, but I am suggesting cars with higher miles, thus used regularly, are likely to have had their key fobs used (significantly) more than garage queens. Do you have any further info about keys having a limited number of uses and what this actually is? Have been using the same remote key on my VW for the last 14+ years and struggle to see why / how this would be different for another manufacturer. These keys are relatively simple transmitters. There is the potential that if you have a duff key with an intermittently stuck button - or - you the button is somehow pressed (a lot) when not in the vicinity of the car, they become "out of sync" as they use rolling codes. Either way, why the OP's alarm is going off is nothing to do with the key. Ash, read the JMG article it details this phenomenon. The biggest offender for this suspected as 'pocket fiddlers' who sub consciously press the button or kids playing with the keys and it can be a PO not just current owner, so not age or mileage related, just number of presses. I agree, the alarm the going off is not related to the key as you say, looking at reasons the key is not working too though. Quote Link to comment Share on other sites More sharing options...
K.I.T.T. Posted January 10, 2022 Report Share Posted January 10, 2022 Thanks for sharing the JMG link. Apologies for the slight tangent, as this isn't related to the alarm issue... Highlighting the relevant portion from JMG below: Designed in planned obsolescence - This I feel is a little bit naughty of the designers, or a very simple honest mistake in design. Once the code in the remote has rolled a pre set number of times, after literally hundreds of button presses, it will not be able to roll any more due to how the software was programmed. The alarm system however will continue to roll the code into infinity, so eventually they will go one step out of sync and the love affair between your remote key head and the alarm control system will be over forever. My question is in practice, how often does this happen? Have heard about buttons failing which is still relatively rare, but does still happen. Have yet to see the above happen (or be mentioned) in practice. Again, say 150,000 miles in 20 years. IE 7,500 a year. Even at say 150 mile per trip and 2 presses of the button, once to unlock and once to lock, that's like 100 presses minimum a year. Times 20 years = 2,000 presses. Now bear in mind, that's the absolute minimum. In reality, over 20 years for those miles, I'd expect the actual usage to be closer to 10,000, if not more. Yet our original remotes are still working just fine... Quote Link to comment Share on other sites More sharing options...
TROOPER88 Posted January 10, 2022 Report Share Posted January 10, 2022 Circa 20-30% of the 986's I have dealt with have required a new key coded to the car due to loosing synchronisation. Wet immobiliser units - never seen one Quote Link to comment Share on other sites More sharing options...
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