Anyone used one of these. Goes off when a door is opened? http://www.laleisure.co.uk/motorhome-guard-plug-158-p.asp
http://www.vwheritage.com/vw_spares_Courtesy-light-switch-T25-Handbrake-warning-light-switch_act_shop.product_pID_49077_lang_EN_country_GB.htm?crumbStartRow=26 I have one of these on each door pillar - works, although sounds like a fly stuck in a coke can when triggered.
I bit rubbish i am afraid It looks like it just detects a volt drop so if you have charger or anything that takes power it will go off but as others have said just pull it out and it will stop
Things like this are actually intended for use when you're in the van camping. Most modern alarms have internal movement sensors, tilt sensors, infra red etc, which means that you can't engage the alarm when you're camping inside, as any movement will trigger it. These are intended to wake you up if anyone gets into the van whilst you're sleeping. So on that basis quite a good buy
You'll need a cigarette lighter socket and not be on hook up. You'll also need to be all doors closed (so no awning) - and any thief will need to open the front doors only, and for you to have the courtesy light switched on. Other than that - £46 sounds like a bargain for electrics that add up to maybe £3. There are better bits of kit out there for a fraction of the cost.