 | Home > In Car Electronics > My 2011 Defender's Alarm Goes Off! |
 
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| Alun Member Since: 22 Dec 2015 Location: Snowdonia Posts: 34   
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My Defender's alarm goes off inadvertently to the point where I can't leave it locked, it goes off when I've locked it with the fob usually after 1-2 hours without warning. I've checked the fob battery and the vehicle battery and all seems ok there. Any suggestions? I've been told that there is another "backup" battery in the alarm but I can't find any reference to it or where it's located?
Thanks in advance of any replies and help |
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21st Jul 2021 12:17pm |
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| Alun Member Since: 22 Dec 2015 Location: Snowdonia Posts: 34
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Thanks camelman - I'll check that out too but its not happened just in the last few days
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21st Jul 2021 12:37pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17384 
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A couple of thoughts. Firstly, do you have access to a diagnostic tool that can read the 10AS alarm ECU? If so, it will tell you which sensor has caused the activation.
Secondly, do you have a volumetric sensor? Most Defenders have both perimetric and volumetric protection. The former protects the opening panels (doors, bonnet) and the latter detects movement within the cab (so that the alarm sounds if a window is broken, etc). I notice that you appear to have a truck cab and I don't know if it would have both. You can isolate the volumetric sensor either by popping out of the headlining and unplugging it, or by sticking a small patch of duct tape over the sensors, and this, in the absence of a diagnostic tool, might help isolate what is triggering it. The "backup battery" you have heard about is probably the BBUS or battery-back-up-sounder which ensures that there is still a lot of noise if the main vehicle battery is disconnected. This was on the whole an optional extra (standard for a few years on a few specifications though) and is really essential given the ease with which the vehicle battery can be disconnected without opening anything. Unfortunately in a moment of sheer genius of the kind only Landrover can manage, it was put in a location where it too can be accessed from outside the vehicle without setting off the alarm, thus greatly reducing its efficacy. If you do have one, it won't be the cause of your alarm going off, although it may well be making it much louder when it does. The alarm used the cab door switches to detect when a door is opened, and these do not have a good reputation for reliability. It may be that a sticky door switch is to blame. Does the cab light come on reliably when either of the doors is opened? Last edited by blackwolf on 21st Jul 2021 1:35pm. Edited 1 time in total |
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21st Jul 2021 1:34pm |
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| landy andy Member Since: 15 Feb 2009 Location: Ware, Herts Posts: 5707 
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When it goes off are the doors still locked or now unlocked?
Also try covering, or disconnecting the internal sensor incase it’s just sounding at flies etc. |
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21st Jul 2021 1:35pm |
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| dorsetsmith Member Since: 30 Oct 2011 Location: South West Posts: 4554 |
Or lock it with key and internal sensor is not set as per owner manual if you need to level dog in land rover but not in this heat 98 f out side to day
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21st Jul 2021 1:46pm |
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| Balvaig Member Since: 19 Feb 2016 Location: Fife Posts: 730  
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If you have volumetric sensors, found up by the roof, they can be triggered by air movements or flying insects. A simple test is to lock the car using the key in the drivers door. This arms all the perimetric sensors, ie doors , bonnet but disarms the volumetric sensors.
Then wait and see. |
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21st Jul 2021 1:46pm |
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| Alun Member Since: 22 Dec 2015 Location: Snowdonia Posts: 34
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I've been away and come back to even more great answers! Thanks Balvaig, Dorestsmith, Landy Andy and Blackwolf - these are all great suggestions and I'll give them a go tomorrow
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4th Aug 2021 8:20pm |
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| Alun Member Since: 22 Dec 2015 Location: Snowdonia Posts: 34
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In reply to your suggestions Blackwolf....
"A couple of thoughts. Firstly, do you have access to a diagnostic tool that can read the 10AS alarm ECU? If so, it will tell you which sensor has caused the activation. Secondly, do you have a volumetric sensor? Most Defenders have both perimetric and volumetric protection. The former protects the opening panels (doors, bonnet) and the latter detects movement within the cab (so that the alarm sounds if a window is broken, etc). I notice that you appear to have a truck cab and I don't know if it would have both. You can isolate the volumetric sensor either by popping out of the headlining and unplugging it, or by sticking a small patch of duct tape over the sensors, and this, in the absence of a diagnostic tool, might help isolate what is triggering it. Yes, mine has both sensors The "backup battery" you have heard about is probably the BBUS or battery-back-up-sounder which ensures that there is still a lot of noise if the main vehicle battery is disconnected. This was on the whole an optional extra (standard for a few years on a few specifications though) and is really essential given the ease with which the vehicle battery can be disconnected without opening anything. Unfortunately in a moment of sheer genius of the kind only Landrover can manage, it was put in a location where it too can be accessed from outside the vehicle without setting off the alarm, thus greatly reducing its efficacy. If you do have one, it won't be the cause of your alarm going off, although it may well be making it much louder when it does. Yes, this is the part I'd been told about. I was hoping to eliminate other reasons before ordering one as there around £150 The alarm used the cab door switches to detect when a door is opened, and these do not have a good reputation for reliability. It may be that a sticky door switch is to blame. Does the cab light come on reliably when either of the doors is opened? wouldn't describe it as totally reliable - I'll try adding some WD40 to ease it |
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4th Aug 2021 8:28pm |
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| Alun Member Since: 22 Dec 2015 Location: Snowdonia Posts: 34
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Well, I seem to be getting somewhere - two steps forward but one step back I'm afraid!
I tried the suggestions above and its definitely the volumetric sensor. I've ruled out the perimetric sensors on the doors and bonnet and the Landys now able to be locked up without the alarm going off, albeit that the volumetric sensor is disabled for now. What is the solution to this (clean sensors/new sensor/maybe new door seals??) When I went to lock the cab with the ignition key as suggested, it was completely solid (key went in but didn't turn). When I lock it with the alarm fob, this locks the doors and the barrel moves a couple of degrees. Its very possible that the key hasn't ever been turned and the barrel has seized - any suggestions please? I've owned it since it was three years old and I'm unaware that the ignition lock has ever been changed but I guess that's a possibility? |
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5th Aug 2021 12:45pm |
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| Balvaig Member Since: 19 Feb 2016 Location: Fife Posts: 730
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For a quick and simple test, try spraying Wd40 into the lock and then gently trying the key. The lock is probably full of dried gunge, although as you say, the lock may have been changed.
This may work, but there are more drastic measures. Nearly everyone has some lubricating spray handy. |
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5th Aug 2021 2:11pm |
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| glpinxit Member Since: 31 Jul 2010 Location: rural Somerset Posts: 156
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Spider?
Once upon a time the alarm went off at 03:00 in our 'other car'. I pressed the plip to shut it up and went back to bed. It went off again as I was dropping off so I went out with a torch. As I was sitting in the cold and dark and feeling sorry for myself a little spider dropped down in front of the sensor. I grabbed it and went back to bed and no further interruptions. Since then I've occasionally sprayed fly killer round inside our cars- particularly I notice webs in them. Cheers, Guy. |
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5th Aug 2021 5:21pm |
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| Alun Member Since: 22 Dec 2015 Location: Snowdonia Posts: 34
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Thanks and due to everyone's help, this is now sorted! I've changed the door seals and used fly spray to remove any spiders from the corners and it now work flawlessly
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28th Aug 2021 6:36pm |
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