best place to wire in an immobiliser switch?

[salviablue]

where would be the best place to wire in an immobiliser switch and how?
Regards

[83Excel]

Have you considered one of these. They bolt straight on to the battery and as you have to open the boot with a key should be secure (at least on the older models you need a key not aware if the newer models have a remote boot latch).

http://cgi.ebay.co.uk/RICHBROOK-Quick-R ... 7C294%3A24

[robertverhey]

My immobiliser (a VDO aftermarket item) is physically mounted behind the driver's footwell side panel, there's just room for it there. So it's completely out of sight. It immobilises two circuits, the solenoid trigger feed and the fuel pump. Maybe a third, can't recall. It's also combined with a VDO remote central locking unit, with non-original locking switches replacing the factory fitted ones in the doors. All works a treat.

[amarshall]

There is also room for an immobiliser on the back of the panel which holds the dim-dip module in the passenger footwell.

[KevW]

I've got one of those Dis-car-nect units (mentioned by 83 Excel). It's not the most secure anti-theft measure but I find it's real value is as a quick and easy way to isolate the battery when I'm working on the car. All you have to do is twist the knob and remove the in-line fuse.

[salviablue]

Hi guys,
Thanks for the replies.
Should have made my request a little clearer (did it via mobile, bloody t9)!
I was thinking more of making a simple latching circuit from a relay, a cap and a couple of hidden but easily accessible switches. One switch to power the other via the relay (or relay latches on for what the 2nd switch switches) which in turn needs to be switched to enable the car to power the dizzy or some other vital-engine-running-electric-component, then the first switch switched off or position 3 to allow the car to start, with a time delay that if its not done in sequence and car started with in a certain time limit, the circuit resets (to give potential thieves more headaches and to leave the "immobilizer" armed if I was to go to start the car, disabling the immobilizer, then change my mind, leaving the car startable).
I am going to stick in a little flashing led (simple flip-flop circuit) for when the system is armed, just to add a deterrent and add a visual indicator to an alarm/immobilizer.

So the idea:

switch 1 pos 1 = dizzy off, sw2 off
sw2 pos off = coil off

sw1 pos 2 = dizzy off, sw2 live
sw2 on = coil live (latched on via relay)

sw1 pos 3 = dizzy on
sw2 pos on = coil live => start car within 30 secs else cap fully discharges and relay loses power, switching off the live feed to the coil.

Does this sound feasible? Would the dizzy and coil be the best places to tap into as indicated? Would any where else be better?

One of those discarnect units would be a good idea but I am going to wire/cable in a boot release (although, I am thinking that if I have an electronic boot release, then I may wire it so it will only release with the handbrake and ignition on.) even if its just for a quick way of isolating the battery a-la KevW

Cheers, if you can follow my rather confused style/thinking!

[robertverhey]

Yep, way over my head! I just follow the insrtructions on the box! Both immobilisers I've fitted have stressed not to use the lead between coil and dizzy as one of the circuits to be diasbled. Not sure why. Maybe they don't trust their own product. Fuel pump and ignition switch to solenoid are two obvious ones to disable....third? not sure.

Robert

[salviablue]

Right, I think I have it sussed. I'd rather not give out the diagram until I have been able to at least test it to confirm it works. Unless ofcourse there is an (auto)electrician amongst us that may be able to avert any possible headaches/disaster and review it.

I settled for using the fuel pump, coil and starter feeds, would have to cut into the bonnet/boot wires as opposed to the relays as that would be too obvious for a seasoned tea leaf/hot wirer. Although, I have a cunning trick to disguise the whole system (wires, relays and switches) as usual standard stuff, so hopefully any potential theft would be left banjaxed from the get go. (ie be looking in totally the wrong place)! Plus the chances of getting the right switches and combination/order would be minimal.

The basics:

sw1 pos1 = coil live : starter dead : fuel pump dead
sw1 pos2 = c, s + fp dead but starter "activator" armed
sw2 push = starter live
sw1 pos3 = c + fp dead but fuel pump "activator" armed
sw3 push = fuel pump live
sw1 pos1 = all live

Once the car is in motion only the coil can be accidentally de-activated by catching switch 1.
With the "immobiliser" armed, two red leds will blink. One led will extinguish for each of the starter and fuel pump circuits are made live. Once the switch is thrown back to pos1 a green led will light. Thus, two blinking red leds = system fully armed; green led = system disarmed, car startable; any other combination = system not fully armed, car non-startable via normal keyed ignition.

This uses a mix of relays and feeds from various circuits leaving the original circuits feeding as intended except for the interception of the "immobiliser" system.

Once I can confirm this to work I may attempt to include a system whereby anything done in the wrong order resets the disarming procedure and also a fault indicator.

It is in the crude state and even if it does work initially I may need to smooth out the current to stop spikes/falls in charge from interfering with the relays thus causing problems whilst running.
Being unfamiliar with some of the relays used I don't as yet know whether contact bounce may effect their operation, and indeed how much contact bounce there may be.

Any one interested for pure research intentions may pm me for a piccy of the diagram for furtherment in this matter. (this is where some one whom knows exactly what they're talking about blows my theories out of the water!).

[bash]

My wife just gives me the T.V. remote. That seems to do a good job of immobilising me !!

Bash

[Ozzy_UK]

Have you considered one of these. They bolt straight on to the battery and as you have to open the boot with a key should be secure (at least on the older models you need a key not aware if the newer models have a remote boot latch).

http://cgi.ebay.co.uk/RICHBROOK-Quick-R ... 7C294%3A24

that assumes you can lock your boot !!!