Alarm Triggers for No Reason

[ericksd]

Anyone ever have the alarm go off every so often for no reason?

Actually there is a reason...my diagnostic software says volumetrics.

These (I believe) are the motion sensors inside the car.

Just wondering if anyone has had any luck repairing or replacing.

99 Disco 2 (pretty much stock)

Dan

 

[joey]

there is not motion sensor in the vehicle, unless you have added it after market.

The fix is probably the hood switch for the alarm that need adjusted.

 

[Moose]

The motion sensors inside the truck were in there through (IIRC) 1995. Apparently too many kids and dogs were setting the alarm off!

 

[ericksd]

Believe me, my truck has motion sensors from the factory. Sounds like they actually detect changes in air movement.

Here is what I found so far in my shop manual...

-----------------------------------------------------------------------
The BCU uses volumetric sensors to detect any change in air movement within the vehicle. There are two sensors
located in the headlining of the vehicle.
InpvVoutput
The sensors require a regulated power supply of 12 volts, via the BCU. When a change in air movement is detected
the sensors generate a 5 Hz pulse train to the BCU.
Each of the sensors have a dedlcated signal input to the BCU. Power to the sensors is supplied by the BCU.
TestBmk provMes the ability to monitor the real time state of the sensors.
-----------------------------------------------------------------------

 

[joey]

Well this is news to me.... Didn't know the Disco's came with this option. I would say that replacing shouldn't be to hard, cost may be high...

But if it was me... I would go to my Friendly neighborhood LR dealer and ask then just to turn that off in the BCU so that they don't work any more. Probably cheaper than fixing the issue. But then again, I don't worry about any one breaking into my Disco... the doors are normally unlocked anyways.

 

[disco1]

I've never seen one in a Discovery either. The early model RR had them mounted up near the mirror as best as my memory recalls.

 

[paulbrapp]

I always wondered what that blank space was near the drivers head!

 

[ericksd]

I think I'm just going to try unplugging one at a time and see if I still get any false alarms. New one (for rear anyway) is $185 from Rovers North.

 

[disco1]

If there's one thing I hate it's alarms. I once spent an hour in the wilderness, in pouring rain, trying to find the alarm control box that the installer had hidden under the dash, then, pulling apart the steering column on my 91" to disconnect the wiring on the alarm system, that decided to shut the engine down. I have since fitted a simple ignition cutoff switch, leaving the blinking red "alarm activated' light that was fitted with the system, in place. This light blinks constantly, whether the cutoff is activated or not.