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benh78

Member Since: 29 May 2018
Location: UK
Posts: 15

2015 Defender 110 Puma 2.2 USW Santorini Black

Defender Alarm Weird Fault

Hi

My 15 plate 110 Defender's alarm has got a weird fault. It arms fine with no false alarms and disarms fine and doors unlock as they should. But as soon as I turn the ignition on the battery backup siren (BBUS) goes off. If I then turn the ignition key off the horn also goes off and it all gets quite loud and annoying for all my neighbours. Ignition back on or start the engine horn stops but BBUS keeps on going off for a while.
Engine starts no problem so I just start it and after about a minute the BBUS just gives up and everything behaves as it should. It seems to be getting worse i,e 1st time it did it didn't do it again for a week now it does it every time the ignition is off for a few minutes. On the plus side the BBUS seems to be going flat so goes off for less time and is quieter.
So far I have:
Tried the spare fob - no change
Disconnected and reconnected the battery following the procedure in the manual - no change
I've got a BBUS relocation loom that's been in for a while check connections pin look brand new. Metered out the extension loom and that seems fine.

Will now get it booked in with the dealer but whilst I wait on them to fit me n hust wondering if anyone has ideas - I'm thinking it needs a BBUS unit but not sure how reliable and what their lifespan is.

Thanks

19th Feb 2019 4:46pm

NormanD

Member Since: 12 Aug 2011
Location: Bristol
Posts: 286

My 65 plate was doing something very similar, alarm going off randomly and no power to the electrics. Losing the radio codes. It was found to be a bad negative connection on the battery post, looked ok but was intermittently causing the issue, it's a crap design of connector, eventually resolved by tapping the connector further onto the battery post and re-tightening the clamp bolt.
No issues since NormanD WE191

2015 110 XS Utility
2014 VW Caravelle 180 Executive

19th Feb 2019 4:52pm

benh78

Member Since: 29 May 2018
Location: UK
Posts: 15

Hi

Thanks for the tip. My negative terminal looks good - I don't lose power to anything and have had the battery tested. But maybe it is a voltage drop somewhere when the ignition comes on.

19th Feb 2019 5:26pm

discomog

Member Since: 09 May 2015
Location: Notts/Lincs Border
Posts: 2526

2015 Defender 90 Puma 2.2 XS CSW Santorini Black

I had a similar problem a couple of years ago on my 2015 90. The BBUS sounded in the middle of the night on two occasions for no apparent reason. It went off a third time for about 20 secs and then silenced, immediately the horns then started to blow continually. The dealer changed one of the horns, apparently corroded and has been ok ever since. Just wonder if one of your horns is faulty as it seems to be a similar fault. Defender 90XS SW
Mini Countryman Cooper S
Morgan Plus 8

19th Feb 2019 6:03pm

benh78

Member Since: 29 May 2018
Location: UK
Posts: 15

Thanks for that I'll take a look at the horns see if there is any corrosion

19th Feb 2019 6:05pm

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