Vehicle & Technical > Discovery
Webasto Pre Heater & Alarm sensors.
96Disco:
I've had the same problem, after some experimentation I've found that setting the blowers to use the dashboard and footwell vents (rather than the screen and footwell vents) doesn't trigger the alarm.
Best regards,
Phil.
--- Quote from: "Andy." ---
--- Quote from: "Matt_H" ---you'd need to work out if you can cut the feed to the sensor without setting the alarm off first.
--- End quote ---
How can I tell this :?:
--- Quote from: "Matt_H" ---If you can and you can work out which one to cut (note you'll need to cut it from all sensors unless there is one main ultrasonic connector on the alram control) then you need a change over relay
--- End quote ---
According to the work shop manual, there is one main ultrasonic sensor module connected to the alarm ECU.
The rest of the alarm is made up of a bonnet switch, door switches, the lock barrel and sill buttons.
If I can cut the feed :?: there are two sensor wires going to the ECU so these can be wired to the relay unit :?:
There is a connection in the work shop manual wiring diagram for a Fuel burning heater unit to the ECU to I presume LR pre thought of this problem :?:
And where is this ECU the manual has it down situated in the steering column is this correct :?:
--- End quote ---
Andy.:
Cheers Phil.
I've set it again tonight but this time with Pauls tip so we'll see what happens :?:
The thing is it's ran twice before since fitting and never had a problem, this time it just caught them right. The same thing happens if I leave the front sunroof open with the Discovery locked.
I also learnt tonight that some models were fitted with an output which disables the vehicle volumetric alarm when it swithes heater fan on.
Also fitted can be a cutout which switches heater fan back off if the voltage of the main battery falls below a preset point.
I've sent Webasto an email to see what they advise :?:
On your point in may well work switching the vents, but the whole point is to have the vents on the windscreen to demist/defrost on a frosty morning.
We shall see :?:
Gary:
Hi Andy
do you have anything in your vehicle that can be moved when the fan cuts in ie a hanging air freshner from the rear view mirror or god forbid fury dice :lol: :roll:
It may be that something moves in the vehicle when the blowers activated and then the ultrasonic will pick that up. They pick up on movement rather than changes in heat. They are not PIR's (Passive Infra Red detectors) as you would use on a conventional house alarm which pick up changes in heat patterns.
Having said that they may be sensitive enough to the actual movement of the air.
It's just a thought mate.....something else for you to consider.
I would be reluctant to cut into the cable feeding the ultra sonics because the wires in side the cable are relatively fine and fragile. I'm not sure that they operate like a conventional house hold alarm detection zone where you would have 12v pos + Neg - and 2 pairs of Normally closed loops, 1 being a 24 hour tamper loop and the other being Alarm activation loop, which would be easy to use a relay to short out a Normally open circuit from an Alarm activation.
There must be another way round this. I'm sure webasto/eiberspacher and I'm assuming your alarm system is a genuine LR unit will have the relative in/outputs to overcome this liitle problem. Get on to both respective technical departments to find out all your options b4 cutting into the ultrasonic/s cables.
Kind Regards, Gary
Oh BTW I use to design and install bespoke commercial/industrial security systems.
These are different from the vehicle security systems but I have a friend who specialises in Thatcham acredited vehicle security systems. If you need more help I could give him a quick call to find out if you have no joy.
He installs theft prevention alarms and phone systems for our local LR dealer in Canterbury. He's always really busy so I'll only try if you have no joy your end.
Good luck and if you need some extra help just email me and I'll track my mate down for you. :wink:
gary@n-gage4wd.com
NeilWilson:
I had my alarm go off a few times with my Webasto just after I had installed it. I now use the fan speed setting 1 & the screen vent setting. Hasn't happened again. I did contact Webasto & somewhere I have a pdf of a circuit change for fitting an alarm sensor relay to isolate the ultrasonics. Although the pdf is for a Defender the ciruit is the same. If I find it I will post it.
Neil
Andy.:
Now then Gary you might have something there :idea:
I have an Evil Duck hanging from my rear view mirror. This is my second unit and it never happened with the first and no evil duck too. I tried Pauls tip last night and no alarm this morning so I think the duck has to go, will try it and see :?:
Got a reply back from Webasto and received the same circuit change pdf file Neil and yes it's for a Defender system but if all else fails looks simple enough to install but would rather not.
I'll monitor it over the next few cycles, cheers everyone for your input :wink:
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