Tonight as we prepared to go to bed the devil seems to have taken over our RR. The horn started blaring and no matter what I did it continued intermittently. I tried spraying wd40 on the door locks and bonnet latch in case there was a sensor somewhere but with no success. Eventually I disconnected the battery and am now going to bed. Any thoughts or suggestions on the source of the issue would be very helpful. Crazy machine.......

buy some ear plugs, i suspect it was getting cold and lonely

Did it stop when you unlocked it? I recently had problem with the alarm going off and it was diagnosed as a faulty bonnet sensor. Had this replaced and (touch wood) not had an issue since.

no! I tried turning on/off, short driving, open and closed all doors and bonnet. Eventually disconnected battery.......

The same thing happened to me after the AA man changed my battery, when we were manhandling the bonnet
into the service position and locked it, i noticed the bonnet was flexing quite a bit. So I suspect the switch plunger
wasnt close enough to the bonnet inner skin to set itself to the off position.

Anyway, later in the evening the same day the alarm kept going off, on a hunch I unplugged the bonnet alarm switch, sorted!!!.

+1 for the bonnet switch, mine on the disco was playing up a couple of weeks ago, kept setting the alarm off! There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
KIA E-Niro 4+
2021 Discovery 5 D300 MHEV commercial

If not the bonnet sensor, try locking the car with a double press, to deactivate internal sensors.

I had a big (and I mean big) spider running around in the car after shifting some old stuff for my father, kept the alarm going off middle of the night when "he" was moving about. .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

^+1

Was the bonnet sensor on mine. Graham

____
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I also vote bonnet switch. In my case the plastic bracket holding the switch had cracked which allowed the switch to drop and simulate the bonnet being open. ______________________________
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Guy in the local garage fixed it - I was told bonnet sensor but now the horn does not work. Why would disconnecting the bonnet sensor stop the horn from working?

Had a look at the wiring diagrams for '02 - '05 (so might be different on your later model), the horns and the alarm system do not appear to be connected in any way.

Worth checking fuse 10 and 53 (related fuses for above model years) for horns.

What exactly did the "guy at the local garage" do ? .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999