Discovery alarm

My 1995 Discovery has the standard LR alarm on it. Occasionaly the alarm
goes off. I cant find out whats setting it off, I think its probably the
internal sensors as when I lock the doors with the key it never goes off.
For now I have unplugged the alarm hooter. Do these sensors go wrong and
give false alarms? I thought it may have been a fly or spider inside (as I
found a cobweb!).
Any ideas?
Thanks
Richard
V8 90 auto
V8 Discovery

Richard wrote:
> My 1995 Discovery has the standard LR alarm on it. Occasionaly the alarm
> goes off. I cant find out whats setting it off, I think its probably the
> internal sensors as when I lock the doors with the key it never goes off.
> For now I have unplugged the alarm hooter. Do these sensors go wrong and
> give false alarms? I thought it may have been a fly or spider inside (as I
> found a cobweb!).
> Any ideas?
> Thanks
> Richard
> V8 90 auto
> V8 Discovery
>
>

Richard,
A fly or spider would only set it off if you had the ultrasonic sensors
installed. They look like a couple of fresh air vents from a commercial
airliner and they are found in the overhead in the same location that
you would have the HomeLink transmitter. My kids have been trying to see
how hard they need to rock mine before they set it off.

Anyway, I give you a quick test procedure to follow.

1. Starting conditions: ignition off, doors unlocked bonnet switch
depressed.
2. Carry out instructions 3 through 7 within 8 seconds.
3. Release bonnet switch.
4. Switch ignition ON.
5. Lock doors.
6. Switch ignition OFF.
7. Switch ignition ON.

If the alarm is correctly accessed, the horn will sound and the dash LED
will flash. The following check can be made:

8. Open and close any door - LED will light.
9. Depress bonnet switch - hazard lamps will flash.
10. Check engine cracking is disabled. Do not off ignition.
11. Check ultrasonic by operating handset, LED will emit one 5 second
flash and will flash if interior is disturbed.
12. Turn OFF ignition or press handset to end test. Horn will sound to
end test.

One last thing, I'm showing that the UK models have a frequency of
433.92 MHz. It is possible that if you live near a RAF base or an
Amateur Radio operator (I am one, W8JSA) that your vehicle is receiving
the signals and it's confusing the alarm ECU. Just a thought.

--
Jeffrey S Austin
Chesapeake VA

“I fight what you fear, the Red Devil”