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Wiring diagram for the use of a kill/cut off switch


rapandi

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Hi Team,

 

recently I upgraded the wiring for my headlights on my 2002tii using relays for the low and the high beams. I learned a lot about how relays work in general. Feeling inspired and wanting to explore more I got thinking as to how I can wire a toggle cut off switch in the car. 

 

What I want to do - Have a cut off switch (like the one below) that can be flicked to prevent anyone from starting the car up. Switch would be in the car hidden somewhere.

 

668395081_spdt-on-onjpg.jpg.2bd5fcdd46a88e6166007a31f9cea729.jpg

 

So I can came up with the following circuit diagram. Its plain and simple and mind you I am not really any good with electronics. So this is all new for me.

Slide1.thumb.JPG.cffd592b19386a84725fe6e017a00da2.JPG

 My thought process: - In order to start the car I would have to push down the brake pedal which would engage the 85 to 86 connection on the new relay.  There would then be one of three possibilities as follows:

 

1) If the toggle switch is in the off position then it will not complete the circuit thus not allowing the starter to function and therefore the car will not start.

 

2) If the toggle switch is in the "ON-1" Position the starter motor shall receive current allowing the car to be started.

 

3) However if the toggle switch is in the "ON-2" position then as per my thinking it should set of the horns. I thought about how the circuit works for the horn. Currently, without the cut off switch. the horn button would have to be depressed. This would then complete the circuit by engaging the solenoid between 85 and 86 on the horn relay. There is constant live current being supplied to 30 on the horn relay. This would then allow current to flow from 30 to 87 thus setting the horns off. So I thought all I would need to do is by pass the horn button and have the toggle switch ON-2 connected to 85 on the horn relay. Is this correct??

 

Question -  is my diagram logical? Will it work the way I want it to? I am unsure about if my connection from toggle switch to the horn relay is correct?

 

Any criticism is welcome to aid me progressing forward :) 


Regards

 

Raj

Raj

1972 BMW 2002 Tii - Golf Yellow

 

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Is what you are trying to accomplish as follows?

A.) Must have switch on (Pos. 1) and foot on brake in order to start car.

B.) With switch in Pos. 2, car does not crank but horn sounds if start attempted.

 

This circuit isn't there yet, but if that's what you're going for, we can probably get there.  The complications are that the horn is a ground-trigger circuit, unlike most everything else on the car which is 12V triggered.  Also, you need to include the factory starter relay in your planning, if one is present in your car (late model squarie or automatic).

Edited by AustrianVespaGuy
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47 minutes ago, AustrianVespaGuy said:

Is what you are trying to accomplish as follows?

A.) Must have switch on (Pos. 1) and foot on brake in order to start car.

B.) With switch in Pos. 2, car does not crank but horn sounds if start attempted.

Bingo! That's exactly what I want to achieve.

 

48 minutes ago, AustrianVespaGuy said:

Also, you need to include the factory starter relay in your planning, if one is present in your car (late model squarie or automatic).

Mine is a 1972 2002 Tii Roundie manual. As far as I know there is no relay factory starter motor relay.

Raj

1972 BMW 2002 Tii - Golf Yellow

 

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That's an awful lot of trouble to go through for theft-proofing, and won't help a bit if the thieves have a flatbed truck! 

 

A simple kill switch hidden in an unlikely location--or in plain sight, disguised as something else, is just as effective.  A car thief wants to get in and get going as quickly as possible (before you show up with a hand cannon or shotgun), and even 30 seconds of delay when the car doesn't start after he hotwires it is enough... And don't forget you have a steering wheel lock that must be extracted with a slide hammer, even if the thief does get the engine started.  

 

mike

 

PS--my 15 thousandth post!

Edited by mike
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'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
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