Ignition kill switch

I want a switch that will allow me to switch off engine without the ignition key. This switch also will act as a theft prevention device - when it is off, the vehicle won't start at all...Any idea how to put it together?

There are conflicting advices on this which involve cutting power supply to fuel pump, ignition coil, injectors etc either individually or severally. Which would be a good way to do it? I want to mimic the way ignition goes from accessory to ON and vice versa, through another switch / switch + relays etc..

Gyani Jan from the members are requested to kindly guide me to get this implemented.

yes buddy, its simple and can be done at any local workshop,where you can rely on the Electrician.

Dont exactly remember which wire they cut-off to put in that switch-had it in my m800 a long time ago.However,my understanding says that they should cut-off the wire from the ignition and provide that switch(under the dash so that no one can see it) And, if any other mechanic have a look(under your supervision) at it...should be able to understand the brains behind it & should not use any Hit & Trail methods to start the car.

I dont know about NOIDA but yes i know a good mechanic for this near Janak Puri(West Delhi) as earlier i use to live there.

Thanks Varun,

I shall be using this switch not only for the theft deterrence, but also for switching off the car while coasting in neutral. Therefore I am concerned about the car throwing up ECU codes when done incorrectly. I will therefore be interested also in the kill mechanism, and whether or not it will affect ECU adversely.

So I keep this alternative (go to Janak Puri and get it done from  your electrician) as the last resort. Let us still wait for answers...

The ECU will be full of error codes!

Two ways to do this in a car with ECU

1) cut the power to the fuel pump

2)cut the power to the ECU

Both are riddled with problem(obivious) but the problem with modern cars is that the ECU might go into a 'safe mode' sometimes called limp back mode after the interuption in power and the following restart.

This might result in even poorer FE than otherwise.

Also again considering the safety aspect(power steering/brake booster) 'coasting' is an absolute NO on our roads.

I would again recommend a ECU scan tool(which will have the added advantage od an ECU error code reset) rather than the drastic step to cut power.

I know a way to do it without the ECU throwing any codes. We do it day in and day out... Its called the ignition switch...

What I want to do is mimic the action of ignition switch, without cycling the key. The kill switch will be in series with all circuits that the ignition controls, with normal position such that it does not affect anything and is transparent to the electricals of the system. When activated, though, it acts as if the ignition key has been turned from ON to accessories position. I will then just avoid putting in the switch action those circuits that power the odometer. This will avoid the blip in the odometer that is a result of it not recording during the period when the ignition is in the accesssories position.

One more objective of this switch is to avoid the ignition key cylinder wear because of P&G. I know a replacement will be costly, and I am moving proactively to avoid such eventuality.

That would be a really worthwhile i guess.

Could you give a guide as you go about the installation, would really like to take a deeper look.

I think you guys are right ...there is a hell lot of difference between 1989 maruti 800 and todays generation cars and i dont have much knowledge on ECU but i am sure that in Carborator engine there are no ECU(though i am sure.but, u have all the rights to correct me on that).

So, it will be better that you should wait and discuss it a bit more...

The carb 800 does not have a ECU-the ones with MPFI does have though(albeit one with a 2/8 bit ECU).

I think the power to the ECU is NOT lost on key off. (Remember ECU Reset = take off negative lead of battery for 15-20 minutes...)

We can speculate but I want an exact list of circuits that are switched by the ignition switch. Then mimicking it is straightforward.

Why should it be that difficult to get this info...?

@Krishna, what you want is a sort of immobiliser, right?