What are the best wires to bypass for immobiliser circuits?

[SM AUTOS]

Just fitted a toad alarm to my 325i.

Does anyone know the best wires to cut and join into the immobilser circuit?

I have seen alarms before where some fairly heavy duty wires have been cut and joined with the thinner immobilser wires & I'm trying to avoid this.

Any info appreciated.

Cheers

Steve

[SM AUTOS]

Anyone, Brian help please!

[Stan0870]

hello mate,i dont know how much help i'l be, but i'l give it a go until some one with electrical know how gets back to you, its usually the thicker the wire the less ressistance,but dont be temted to put anything to skinny in place as the resistance will be to high an it may melt. ie-headlamp bulb (load resistor) - (skinny wire inside) creates high resistance as current has a job to pass through it,which then creates heat and in the head lamps case -light!. does the unit indicate how much load it will put on the circuit?(power needed to operate) that will give you an indication as to what cable you will need.my alarm seems to use pretty standard automotive cable no more than a couple of mm in diameter. dont know if ive helped you or hindered you!

[Brianmoooore]

There's no really effective way to immobilise an E30. The ignition and starter circuits (the ones most often disabled by "professional" installers are ludicrously easy to bypass). Interrupting the supply wire to the fuel pump is slightly more effective, because the point you need to connect to in order to bypass it, is more inaccessible.
If you have immobiliser contacts that short circuit when active, you can connect these to short circuit the fuel pump wire to earth (after the fuse), in conjunction with some contacts to disconnect the ignition.
Some late ECUs apparently have a pin on the ECU for immobilising (see a Spadge thread from a few months ago), but I have no details on this.

[Beavy_OZ]

I've bought a kit that hooks up to the ingition system and causes a random fault every few (~ 8 ) seconds of driving, makes it a pain in the ass to steal and hopefully they'll just give up and think it's the dud motor, not an immobiliser.

[Brianmoooore]

I've bought a kit that hooks up to the ingition system and causes a random fault every few (~ 8 ) seconds of driving, makes it a pain in the ass to steal and hopefully they'll just give up and think it's the dud motor, not an immobiliser.

Capacitor on the ignition coil negative?

[SM AUTOS]

Thanks for the replys guys.

I think I will interupt the fuel pump feed, and possibly the starter solenoid feed too.

Just don't like cutting and joining wires into immobilser circuits, incase the alarm decides to pack up

[Stan0870]

i know where your coming from mate, it happend with the toad alarm on my mates GTI an left him stranded in town at 11pm at night!, he was'nt best pleased to put it mildly!. whitch craft mate... all hail the electrical gods...

[Brianmoooore]

Best immobiliser for an E30 is a hidden (or not so hidden - mine use a rear screen demister switch, in the demister switch position) switch connected to short the fuel pump supply wire to earth.