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Main relay/ kill switch

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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Hey guys what do people recommend for main relay/ kill switches? Im building a wrx coupe circuit car and am starting wiring from scratch.

I know of tyco relays and the cartek units. what have people found to be the best? my reading of the msnz regs is that it doesn't need to isolate the battery it just has to kill engine and fuel etc.

I look forward to your replies =)


I've had trouble with kill switches and am now looking into high amp solid state switches or relays. It is prudent to kill battery and alternator. With the solid state switching you should be able to have multiple low amp switches that trigger the solid state devices. If you class requires an external mount kill this makes things simple. I'm hoping to run a kill button under the bonnet, in front of the a pillars, transmission tunnel and one near the fuel pump.

I'm not expert and seeking to learn. The plan is also to go full solid state for all relay/fuse power.


Depending on your budget, have a look at the SS isolator www.msel.co.nz has released, its a pretty damn fly piece of kit. He does a club version which has a flying lead instead of the soriau connector, which takes $60 off the price. We've got one to be installed on our 350Z during its next round of upgrades.

Thanks or your replies, looks like a cool product but probably a bit out of my budget for kill switch.

is there any issues with running a tyco relay to just switch the main feed to fuse box? This meets the criteria of shutting down all circuits and the engine. And leaves the alternator and battery connected to avoid a voltage dump.

i know this leaves a live 12v at starter and alternator terminals but possibly not an issue?

thoyghts anyone?

As far as I know for Schedule A you dont even need an isolator, just an ignition switch that will kill the engine. One inside in reach of driver and one outside at the base of the windscreen. The few I have done I have just used a standard waterproof toggle switch in series to the normal ign switch.

You should be fine with one of the tyco relays Richard. If you wire your switches in series, they both have to be on for the system to be powered, so one at the base of the windscreen and one for the driver should be all good :-).

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