Board logo

Master-Cut Off Switch
scootz - 11/4/09 at 10:28 PM

Is there any point in fitting one on a road car? Does it offer the driver anything more than the usual key / ignition barrel?


Ninehigh - 12/4/09 at 12:06 AM

If you hide the switch it'll make a nice anti theft thingy... S'all I know about it


greggors84 - 12/4/09 at 12:08 AM

I have some circuits that are always live, like the hazards, which I think is a requirement. Having a battery cut off means I can isolate the battery completely and as it doesn't always get driven regularly it stops the battery going flat in case there is a slight drain on those circuits.

Also It was one of my 2 immobiliser devices required for SVA. Not sure if that applies to IVA.


matt_gsxr - 12/4/09 at 08:20 AM

I'm with Greggors.

Nice to have when you are messing around with stuff electrical. You know, when you need to do something around the starter lead. Do you always disconnect the battery? with a switch it is easy.

Also the FIA ones are a bit tricky to wire in (i.e. ignition wires, and routing of big power cables), so its difficult to retrofit.

I did have mine on the dash, I rounded off the key all nicely, but the SVA chap said something about >9mm projection, so now it is set back a bit with only half a key!

Matt


big_wasa - 12/4/09 at 08:23 AM

I didnt bother on mine but it would have been handy to isolate it when working on it, instead of taking the terminal of every time.


C10CoryM - 12/4/09 at 04:31 PM

If you're fuel injected you will want to keep your ECM alive with a seperate power source or with a master killswitch bypass. Otherwise it will lose it's memory every time and cost you power and drivability.
Cheers.


greggors84 - 13/4/09 at 11:39 AM

Depends what ECU you are using. I think your right for most OEM ECUs as they are meant to constantly change to get the most effiecient fueling.

But most aftermarket ECUs will have a map stored on the chip that you have uploaded or modified and as far as I know you wont lose that map when the ECU loses power.


C10CoryM - 13/4/09 at 01:57 PM

All ECUs will keep base maps for fuel/timing. However they will generally be very safe maps. Meaning lots of fuel, and not much timing advance. Then it relies on the oxygen sensors and knock sensors to find out how much it can lean it out and advance the timing. This memory will be lost everytime to battery is disconnected.
Cheers

quote:
Originally posted by greggors84
Depends what ECU you are using. I think your right for most OEM ECUs as they are meant to constantly change to get the most effiecient fueling.

But most aftermarket ECUs will have a map stored on the chip that you have uploaded or modified and as far as I know you wont lose that map when the ECU loses power.