Outer Limits 4x4 Board

ok before you all fry my i have searched and found nothing, then i went through 20 pages of this trying to find something..

ok i have a single battary in the rear. the switch is in the rear (only accessable place for team and officials without it getting ripped off)
and i need to have the following..

once the switch is pulled out.
it needs to shut the whole circut down, inc alt, ign,power..

i hooked it up to the earth, didnt work
hooked it up to the power side, didnt work
as above but with the alt also inc and it didnt work..

how the hell does this work?

it is really shitting me as i can wire cars from scratch but the mind has just gone blank on this one.

um ok...

all you people that compete.. er.. thanks for the info..

ill work it out myself as i usually do...

I put mine on the posative battery lead, but ran the alternator output directly to the battery. When the switch is off, the alternator output is still connected to the battery, but they are isolated from everything else. That stops the engine dead, but I guess there is still a wire carrying 12v to the engine bay...
You could use a double pole switch or a solenoid to isolate the alternator completely, but I didn't bother because the cams regs just said the switch must stop the engine, not isolate the battery...

There are only two sources of +12V in your vehicle (unless you have several batteries) - the battery's positive terminal, and the alternator (when the engine is running.)

If you have placed the switch in the circuit so that it completely cuts off both the alternator's +ve side and the battery's +ve terminal, then it should definitely be working fine to shut everything down.

On the flipside, if the engine etc keep running when you activate the isolator, then you must have left something connected that is bypassing the isolator. Your engine will definitely not run without +12V coming to the coil.

I don't think there's any trick to this; you just need to check thoroughly that you are isolating all the necessary cables.

Also, I wouldn't bother trying to put your isolator on the -ve/ground side of things because your alternator is grounded through its body, so it's virtually impossible to isolate.

Jason

got it sorted..

all but one thing.

the 2 4g wires from the engine to the rear of the car where the batt is.
do i need to run both a positive and a negitive?

can i just earth the batt to the body at the rear and also do it at the front onto the body.