Unarmed alarm alarming!!

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Ian.V

Ian.V

Member
Posts
67
Location
Nottingham
Evenin’ all

Any electrical wizards familiar with the defender TD5 alarm system out there?

My vehicle has been standing for a few weeks while I do a few jobs to prepare it for sale.

During all this time the alarm has not been armed.

Last night the alarm went off at random intervals with the horn blasting my neighbours out of their beds at 4am!!

I decided to disconnect the battery and try to trace the fault over the weekend and just wondered if anyone has suffered a similar incident or is maybe able to point me in the direction of the most likely cause,

I’m suspecting that following some of the recent heavy rain something is shorting out?

Any help appreciated

Ta
 
The first thing l would do, is to check all the switches.
The door courtesy light switches, but particularly the bonnet switch.
 
The horn is controlled by the horn switch but can also be turned on by the alarm relay. The alarm relay is connected to the 10AS alarm ecu by an Orange / White wire. Some way along that wire there is a black wire spliced in which goes to the battery backed up sounder / BBUS- this wire is supposed to be continuously held at +12v. If the alarm detects an alarm event it switches this connection to low, which energises the horn relay AND the BBUS. The problem may be for you that the alarm was never armed yet this wire was always now live because of an issue with the splice or within the BBUS (back up battery needs replacing)
Might be worth checking this out first
 
Many thanks for all your info & suggestions.
Just to add a little more detail – I’ve charged the battery up recently during the time it’s been standing for a few weeks, and regarding the BBUS, if it would be a similar looking unit to the one on my Disco3 then there isn’t one on this defender.
Incidentally it's a W Reg 1999/2000

Thanks again
 
Ian.V said:
Last night the alarm went off at random intervals with the horn blasting my neighbours out of their beds at 4am!!
Click to expand...
It may be the case that someone is triggering the alarm until you get fed up of it going off and disable it thinking there is a fault. Once disabled it is easier to steal. Just be aware / alert. (Although as you say it probably is a fault if you had already disabled it).
 
Point taken but they would have to move two other vehicles which are both alarmed before getting to it.
I was wrong when I said there was no BBUS sounder, I obviously hadn't tried standing on my head before searching for it!!
I haven't been able to work on it today but following on from all the info provided by JimS does it follow that if you removed the fuse it would trigger the alarm?
 
The current situation is that the vehicle will not start.
Having difficulty in tracing the fault without upsetting the neighbours so I disconnected the alarm sounder, as whatever I tried didn’t shut the bugger up - including removing all associated fuses and a relay. The only way to stop it is to remove the negative lead from the main vehicle battery. Can someone confirm whether or not removing the sounder would trigger the immobiliser? I would assume it would do as a security measure. If so, is there a way of connecting a jumper wire from the sounder supply lead to wherever?

I previously tried to muffle the volume of the alarm without success probably due to the frequency.

The flashers work as expected when using the fob. Three to arm it and one longer flash to disarm.

Upon arming with the fob the red dash-light behaves normally flashing rapidly for a few seconds and then settling down, but there is no response from the starter.

When turning the ignition key all lights come on and the fuel pump kicks in, would that happen if the problem was the immobiliser? I would have thought that if the vehicle was immobilised the supply to the fuel pump would be cut off.

I’ve checked all the door switches and they all work and have a good earth connection. The bonnet switch doesn’t have a ‘positive click’ action, don’t know whether that’s normal or not. I haven’t had time to remove it yet for closer inspection.

I’m hoping I’ve missed the obvious solution!!

Any thoughts/suggestions very welcome.
 
I have a later model than yours but there may be similarities. Before disconnecting the battery I need to turn the ignition key to position II then to off, and disconnect the battery within 15 seconds (having the earth lead bolt slackened off ready helps). This stops the alarm sounding. If you pull a related fuse or disconnect the battery without doing this, the alarm will sound. You can check this method if you have an owners handbook.
 
When you put the ignition key in, is the fob hanging off the key so it is in proximity of the gadget (transponder?) hidden inside the steering column shroud? And is the fob battery good?
 
Nobber, as mentioned earlier it all started with the alarm going of at random intervals during the night and I'm now in the position of not being able to start the vehicle after removing the alarm sounder.
Regarding your comments Wimblowdriver The key-fob is attached to the key and the fob battery is good.
Do you know if the immobiliser also cuts off the fuel pump? I'm only assuming it's the immobiliser at present
 
Wimblowdriver
I'm not sure I turned the ignition key off again before removing the battery lead within 15seconds.
I'll try again tomorrow, I'm afraid I'm getting to the age where I'll have to write down everything I've tried!!
Incidentally is this sequence intended to mobilise the vehicle as well as shutting the alarm off?
 
Nobber
As mentioned earlier it all started when the alarm was sounding at random intervals and after all my attempts to stop it I finally resorted to removing the alarm sounder and since then I can't start the vehicle!!
 
When you mentioned you were preparing it for sale I thought you might be doing some mechanical work to it.
 
Nobber
I've had it standing for a few weeks while I was doing a bit of bodywork and the alarm problems started.
May have been due to voltage drop but since recharging can't start it.
Thanks
 
Is there any way you might have disturbed anything while doing the body work? Wiring, switches or anything?
 
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