Outer Limits 4x4 Board

ok, so for the toughtracks comp, i have to have a kill switch that shuts down the car when switched off. i've installed one connected to the negative terminal on the batter, so when turned off it shuts down all the electrics, but the motor still runs on the alternator

so, what wire should i hook into to kill the motor??? the car has an efi motor

Switching the negative side of the coil directly to ground normally does a pretty good job - the ECU can't switch the coil to produce spark.

DISCLAIMER: this advice is only worth what you've paid me for it.
Seek independent advice about potential damage to the engine ECU. I don't know how the Vit system works, and wouldn't expect this to cause a problem, but I won't cough up for a new ECU.

Antt, do you need to kill all electrical power- or just stop the engine?

If it's just stop the engine then have a look through the relays in your engine bay. There should be one for the EFI computer, this should be the one that applies power to the EFI computer when the ignition is switched on. Locate the coil wire for this relay and put a switch in that wire.

here's the rules guys

3.3.11 ELECTRICAL
A battery mechanical isolation switch for the battery that provides power to the engine, ignition and fuel pump shall be securely mounted within easy reach of any member of the crew or course official and this switch may isolate the negative terminal.


reading it properly it seems that it only has to kill electrics, which mine already does, so all good

antt wrote:here's the rules guys

3.3.11 ELECTRICAL
A battery mechanical isolation switch for the battery that provides power to the engine, ignition and fuel pump shall be securely mounted within easy reach of any member of the crew or course official and this switch may isolate the negative terminal.


reading it properly it seems that it only has to kill electrics, which mine already does, so all good

the Electrics can't be killed.. cause the motor still runs

find the earth points for the computer and hook them into the kill switch as well, this way it will kill the engine when the key is pulled.

I wasn't going to reply to this post, but I feel it may be prudent in light of the most recent posts...

_D_O__N_O_T_ disconnect the earth from your ECU!!!!! This will result in a 'pop' noise (loudness varying with brand) and your ECU will emit smoke (varying with model). NEVER remove the earth wire as a form of switching for any form of electronics as it can decide to 'earth through other things' after you get floating voltages (that can on occasions be far higher than the source voltage!) and it really isn't good for the little electrickery box thingies...

My friend's rally car has a cable attached to a ring that sits on the rear quarter panel (rear mounted batter) and it can be pulled ot trigger a remote switch that cuts the power. Check that they don't want an external switch access like I just described. You can buy special switches for this purpose and stickers to mark them (they are a big electrical bolt in a triangle).

I would switch the POSITIVE side of your coil, in regard to at worst, you have taken the power from the coil (usually wired as such: battery, ignition switch, dropping resistor, coil, points (or transistor breakers), ground). As opposed to potentially placing a short across the coil to ground (but that would still work).

Remember that you are better to remove power from the device than you are to divert it somewhere - it may decide it is easier to divert to somewhere else!

place it inthe posative battery line this will kill everything.

Switching the negative, as mentioned in the original post, and referred by my above post (should have said this in my last post) is not a good plan as the earth from the alternator is still connected to the engine and as long as charge (self sustaining with engine motion) is still in the alternator, the generation field will continue to exist hence supply power to the ignition system etc. It could well be the simple fix is to swap your kill switch from the negative to the positive battery terminals.

couldnt you tap into the ignition wires? you have 3 on a typical setup...earth, main, and ignition....if you had a switch to cut the ground or main then it would shut down the engine as per normal shutdown

Id stick with the world standard for competition vehicles, a main battery shutoff within a foot or so of the main batt if possible, external acess & marked with the blue triangle as stated earlier. This shuts all power, kills everything, and stops the risk of fire from shorted main cables, melting cables and exploding batteries etc. You can get them in many ratings from 100 amp up to 700 odd amp if needed, the switch and a couple of eye connectors is all you need, SIMPLE.

here you go lads

http://cgi.ebay.com.au/ws/eBayISAPI.dll ... 07051&rd=1

bilby wrote:here you go lads

http://cgi.ebay.com.au/ws/eBayISAPI.dll ... 07051&rd=1

You need to watch it , when isolating the positive side of the battery the cheeper switches tend to fry them selves

bubs wrote:

bilby wrote:here you go lads

http://cgi.ebay.com.au/ws/eBayISAPI.dll ... 07051&rd=1

You need to watch it , when isolating the positive side of the battery the cheeper switches tend to fry them selves

Agree check the load, most of these are rated to 50 or 100Amps Max.
I believe Pirahna now have a 1000Amp switch availble that will lighten your wallets.
I used the pictured switch to isolate the Winch +ve paid the price. Will run the switch via the solenoid -ve now. Simple.

I have just put a kill switch in my lux, if it is off the only power in the whole car is about one and a half meters of cable from the battery to the switch. Didn`t think about the alt but mmmmm might have to think about that one aswell.

Might just put a solinod in the alt wire that is controlled from a wire after the kill switch. When kill switch is turned off the controll wire is dead and the solinod opens which means the power out of the alt can not get any where.

LilBlkDuck wrote:

bubs wrote:

bilby wrote:here you go lads

http://cgi.ebay.com.au/ws/eBayISAPI.dll ... 07051&rd=1

You need to watch it , when isolating the positive side of the battery the cheeper switches tend to fry them selves

Agree check the load, most of these are rated to 50 or 100Amps Max.
I believe Pirahna now have a 1000Amp switch availble that will lighten your wallets.
I used the pictured switch to isolate the Winch +ve paid the price. Will run the switch via the solenoid -ve now. Simple.

Dont pay the 4x4 markup, go straight to an industrial electrical or truck electrics supplier, they use em heaps on trucks and earthmovers etc.

What wire could i put a switch on in my 88' GQ dual fuel? what fuses, relays etc should i use? i have read all these kill switch posts but it gets a bit confusing. i have installed heaps of stereos and speakers and remote central locking so this cant be hard.
thanks