I have discovered an odd trait to my fireblade engined car while preparing it for its CCLB check.

It has a standard MSA battery cut off switch (big red key), the main positive feed to the battery runs into it, the battery positive is not connected to any other point of the car. When the cut off key is out the ignition won't come one and nothing works (as it should be), if you turn the ignition on but the turn off the battery cut off it kills everything (again as it should be). Tonight though I tried the emergency situation, engine running and pulled the marshal handal to pull the battery cut off. The Engine kept running though! All of the other electronics where still running as well (like the digidash). I killed the engine and then everything went off and wouldn't come back on until I turddn the battery cut off back on.

I assume that there is a live back feed coming from somewhere when the engine is running, most likely the charging system amd the cure will be to run that through the battery cut off as well.

Has anyone had this before? Does anyone know what the cure is? Or what part of the charging system needs to be run through the battery cut off?

I didn't wire the car myself and the guy who did has movde to Australia so I'm struggling to work this out on my own.

Cheers

It's running off the regulator, if you have the correct FIA switch not the basic battery cut off there are additional contacts on the back, two make and two break when you turn it.

I have always wired the ignition/injection to the make when closed 'switched on' and for the make when open you run a wire through a resistor to the alternator output so it pulls it down when switched off.

I have seen many cars now when being tested by the scrutineer with driver leaving fans running and lights on because they have not wired correctly.

Back feed will be at the starter solenoid where the reg rec feeds into the battery cable downstream of the fia switch as Mark says
Regards
Andy

I have the FIA switch with the 4 terminals on the back (I think it came from you Andy with the engine and all the other bits)

Which reg/Rec wire(s) do I need to feed into the make /break terminals on the back to kill the back feed?

The ignition break is more important, the switches can only take a low current.

So take the wire that powers the coil pack via the make when switched on contact.

On the engine side of the large red contact run the resistor to the closed when off switch terminal then the other side goes to earth.