Landy Security :(

odenne said:

so point is...which one is it better to isolate? and why does Haynes always say Negative?

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For imobiliser purposes the negative is best. If something doesn't work most people assume it's the live at fault cos the earth is expected to be there. (even if weak). This also applys to most car theives.

disagree - Positive. Every time. The one and only exception to this is in the case of a water-born vessel using a grounded positive DC system (very very rare these days). And even then, you have to remember that a positive grounded system is VERY bad for stray current corrosion in a marine environment. It should be avoided at all costs.

The Mad Hat Man said:

disagree - Positive. Every time. The one and only exception to this is in the case of a water-born vessel using a grounded positive DC system (very very rare these days). And even then, you have to remember that a positive grounded system is VERY bad for stray current corrosion in a marine environment. It should be avoided at all costs.

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For isolating things like a winch, split charger etc. Yes positive is the best. For immobiliser purposes negative.

The Mad Hat Man said:

disagree - Positive. Every time. The one and only exception to this is in the case of a water-born vessel using a grounded positive DC system (very very rare these days). And even then, you have to remember that a positive grounded system is VERY bad for stray current corrosion in a marine environment. It should be avoided at all costs.

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are ya talkin bout earths or isolators?

Shirley from a security point of view positive is better - if its on the negative one and the tealeaves can't find it, all they have to do is short the negative to a bit of chassis somewhere, but if it's on the positive one, they have to physically find the isolator and short it somehow before the thing will start? (or at least find the positive lead to short to the battery terminal) and seconds searching for something is precious when yer pride n joy's bein nicked?

Without giving peeps on here the details on how to bypass a car alarm and stop the alarm sounding and hazards flashing. If a car thief wants to nick a car with a half decent alarm on it he wiill do so by adding POSITIVE feeds to the cut off solonoids starter etc The same as you would do to bypass them when they f**k up. NOT NEGATIVES.
If the same thief wants to bypass a positive battery isolator all he has to do is slide under your car and attach a jump lead straight to your starter motor from a jump pack/battery. Then he puts the other lead to earth anywhere on the chassis. Hmmmmm very secure. NOT. When was the last time you tested a bulb or glowplug etc bhy putting an EARTH to it?
How many earth straps are on a car versus main positive cables?

So what yer sayin? Yer fooked either way?

odenne said:

So what yer sayin? Yer fooked either way?

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think he's saying fit a stereo isolator

Put one on each under each section, probs solved!

odenne said:

So what yer sayin? Yer fooked either way?

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No. You put a small earth to the electrical systems on the dash that require them i.e. to prevent stereo channels being lost, to allow interior lights, hazard lights and alarms and immobilisers to function etc.

These will tell a wannabe thief that the battery is connected. He will then attempt to bypass the alarm and immobiliser by taking positive feeds normally from the battery under the bonnet (but in the case of a deepender the back of the starter) to the imobilisation points in the engine.
Most high performance cars and cars stolen to order which are driven away are stolen in this manner. If the theif is REALLY tooled up he may try to jump start your vehicle suspecting a dodgy battery. With the main earth disconnected it still won't start unless he puts it to the chassis but the moment he disconnects it it will still cut out. Even if he did drive off with the battery or jump pack he is using still connected it wouldn't recharge so it would soon cut out. The wannabe thief will not spend hours testing wiring, especially earths, unless the vehicle is in the middle of nowhere on it's own.

ratty said:

No. You put a small earth to the electrical systems on the dash that require them i.e. to prevent stereo channels being lost, to allow interior lights, hazard lights and alarms and immobilisers to function etc.

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this is a totally impractical suggestion, kindly ignore it

Original fred question was about an 83 defender - no alarm no gadgets no gizmos, fred got dragged towards isolator switches and in relation to the original question they're a simple and good idea which might buy a bit of time if someone is trying to nick your beloved.

Seems it don't really matter which side they're fitted to! It will be quite OK to switch everything off with one switch on this car (you might lose your radio presets if you got something bling in there but it don't really matter) but nothing else will be affected. I swear by mine, it is on the positive lead and works fine (and if you take it out or knock it while the car is going, the car continues to run fine - it's just starting it that you can't do without it)

isolation of the positive, in a place that cannot easily be got to (so the thief cannot bypass it) plus a 12v 2A resettable trip wired across the isolation device IS the best route without a doubt

but if the theif wants your vehicle and has the will power, knowledge and equipment he will have it whatever you do

Sean said:

plus a 12v 2A resettable trip wired across the isolation device IS the best route without a doubt

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now that IS a good idea, genius - i like it.

Sean said:

this is a totally impractical suggestion, kindly ignore it

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How do you work that out. There are battery immobiliser terminals you can buy that do EXACTLY that.

Caravans & Motorhomes Disconnect Battery Terminal (F) on eBay, also, Campervan Motorhome Parts, Campers, Caravans Motorhomes, Cars, Parts Vehicles (end time 14-Apr-08 15:50:15 BST)

now say sorry

ratty said:

How do you work that out. There are battery immobiliser terminals you can buy that do EXACTLY that.

Caravans & Motorhomes Disconnect Battery Terminal (F) on eBay, also, Campervan Motorhome Parts, Campers, Caravans Motorhomes, Cars, Parts Vehicles (end time 14-Apr-08 15:50:15 BST)

now say sorry

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i'm not going to say sorry

just remember what you said that prompted me to make my comment "You put a small earth to the electrical systems on the dash that require them i.e. to prevent stereo channels being lost, to allow interior lights, hazard lights and alarms and immobilisers to function etc."

You made that comment above in support of your "isolate the -ve" case - could you expalin how you'd actually do what your suggesting above bearing in mind that allmost everything metal is a -ve point and would therefore need insulating from it's mating surface if your idea was to be implemented.

That ebay link is just a device which seperates either of the battery terminals it doesnt do what your sugestion recommends which is to isolate the dash and run a seperate feed to it - without lots and lots of work.

The barky dog gets my vote.

go on say sorry an give im a big kiss...yur know you want too

Sirus said:

go on say sorry an give im a big kiss...yur know you want too

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i would if wer wrong, but i wernt - but that dunt mean i want a big un orf him either

Cornt you just pretend to be wrong......just this once

Sirus said:

Cornt you just pretend to be wrong......just this once

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if it keeps everyone appy i might

ratty said:

How do you work that out. There are battery immobiliser terminals you can buy that do EXACTLY that.

Caravans & Motorhomes Disconnect Battery Terminal (F) on eBay, also, Campervan Motorhome Parts, Campers, Caravans Motorhomes, Cars, Parts Vehicles (end time 14-Apr-08 15:50:15 BST)

now say sorry

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This is most useful information from that link...