VK - What side of Coil do I place immobiliser?

[philbio]

Can anyone point me in the right direction?

Do I cut the negative side of the coil (this will then run the switching voltage through the immobiliser) or the positive side (constant voltage)?

[ari666]

funny you should ask that. i have just spent all day gettiung my new, shiny immobiliser installed. got it all up and running and the stupid thing doesnt disarm on primary or secondary. only the third stage works and that is just not good enough.

anyway, as far as i was aware, signal or voltage should be passed through the same from both poles, so if one side of the imm is positive 12V, then when disarmed the other side will be 12V if one side is sig inp 0.3V then so is the other. etc tec cte

[DANNY8]

My Mongoose alarm rekons 15 amps max for the immobilisation points. I guess other alarms would be similar. Would the power to the coil be more then 15 amps? That's one thing I've been curious about. Especially as the ignition wire to the coil is pretty thick, and the immobiliser wires are thin.....just doesn't seem right.

I know earthing out the coil (negative side) will kill the ignition....dunno if it will do any damage to the coil if earthed out for long periods...but if not ya could just wire one imm point to that. Youd have to wire it up through a relay tho otherwise I don't think u could get it to work using that method.

[strgas]

install a relay on the power side of the coil this will drop the 12 volts and kill the spark , grounding the negative side of the coil will work too but not recommend long term damage to coil can occur from doing so

[philbio]

Thanks for all the ideas, so from the feedback it appears the best way is to break it on the positive side of the coil with a relay? The immobiliser I have is rated at 30amp so could go the cheap way and let that do the work alternately.

[ari666]

yeah, i doubt your coil will draw 30A my thermos are fitted with a 20a fuse, so you should be ok.

[philbio]

yeah, i doubt your coil will draw 30A my thermos are fitted with a 20a fuse, so you should be ok.

What other points did you immobilise?

[ari666]

i got electric fuel pump so did that, one of the signal wires from the dizzy and main power to the 6al.

there are dummy wires going everywhere, i worked on it all day yesterday and still have not finished. mate once its done, i would like to see someone take her

[DANNY8]

i got electric fuel pump so did that, one of the signal wires from the dizzy and main power to the 6al.

there are dummy wires going everywhere, i worked on it all day yesterday and still have not finished. mate once its done, i would like to see someone take her

There's only a few wires ya need to get it running tho....so instead of a theif trying to source them all....he could just run new wires. So for the fuel pump, just run a wire from the battery to the pump, will turn it on, run another to the coil (if the dizzy is through the immob, snip them and join them to the + and - on the coil), then use a screwdriver to make contact with the 12v on the starter and the starter solenoid to kick it over. But not sure how the msd's are wired up so that's got me lol.

[Darren_L]

personally I would hook it up via relay to the neutral start switch wiring (connector located at front of console) Even if your car isn't an auto, the connector is still there, it's just bridged. The starter won't even engage if you use this method.

Cutting the coil wire is so common knowledge that it's not very effective.

[ari666]

There's only a few wires ya need to get it running tho....so instead of a theif trying to source them all....he could just run new wires.

which is all good, but i took apart the 6al and changed the output wires to black, so unless they have a lucky guess, they are gonna be there for a while. and the pump wire would last about 2 seconds underneath the car, unless they took the time to fit it up nicely, and the msd/dizzy/coil are all bunched up together under 100 zip ties, conduit and tape i still have not finished yet. just having a breather cos its friggin hot.

also, opening up the safety switch circuit means the starter doesnt kick and would be the first thing you look for. the coil just means she doesnt fire. if they dont notice right away and are cranking for a bit, you may just have time to meet them with your baseball bat/hammer/weapon of choice.

[Darren_L]

the coil is too easy - everyone does it.
If it doesn't fire after the first few hits of the key, first place they will look is the coil and then see the relay spliced in. Dead giveaway. Only then need to pull 2 terminals off the relay, push them together and the car starts. Unlike the starter, the coil is very easily accessible.

[philbio]

the coil is too easy - everyone does it.
If it doesn't fire after the first few hits of the key, first place they will look is the coil and then see the relay spliced in. Dead giveaway. Only then need to pull 2 terminals off the relay, push them together and the car starts. Unlike the starter, the coil is very easily accessible.

I was gonna put the relay under the dash?

[Darren_L]

I was gonna put the relay under the dash?

fair enough that will make it a little less obvious, although the would be theif still only needs to jump a power wire to the coil and it will start.

I guess carbed cars are a lot more difficult to immobilise than EFI cars as most measures can be easily bypassed. I would suggest maybe a secondary immobiliser circuit as well eg fuel pump (if it's electric) or a fuel stop solenoid somewhere in your fuel line. I've got 3 seperate immobiliser circuits connected to my security system to be on the safe side.

[DANNY8]

or a fuel stop solenoid somewhere in your fuel line.

That's a top idea that one, coz the thiefs could get out of ur driveway and it will stall (well depends).....and most prolly wouldn't wanna hang around to see wat the problem is then.

[strgas]

i got electric fuel pump so did that, one of the signal wires from the dizzy and main power to the 6al.

there are dummy wires going everywhere, i worked on it all day yesterday and still have not finished. mate once its done, i would like to see someone take her

havent seen an alarm thats beats a tilt tray yet ???

[DANNY8]

havent seen an alarm thats beats a tilt tray yet ???

Just lock it up in ya shed everynight and keep a rottie or 2 in there with it.

[ari666]

havent seen an alarm thats beats a tilt tray yet ???

yeah, no. no solutions for that one sadly

your gonna laugh, i immobilised my car so well, i cant start it now...

[DANNY8]

haha that sucks...time to go over everything....I hate doing that when something doesn't work. Best way is to use a test light and find out wat isn't working, and work ur way back.

[ari666]

*sigh* after all the wires pulling out, an checking and double checkin' and blady blah blah, turns out it was an earth to the the msd and totally unrelated to the alram, now that i messed with everything my central locking is up the creak and the stereo only has one channel working :S

(self professed wiring guru here)