how to: starter cut-out

dark_knight

dark_knight

Member +
i've been considering something that i think may be possible but need further verification on the electrical schematics of our engines.
in stock form, when the engine is running, and you turn the key to the 'START' position, you will hear crunching and grinding sounds, and your starter or flywheel ring will not like you much after that.. so, i've been thinking.. is there an energized circuit somewhere that is ONLY energized when the engine is running and not when the key is at the 'ON' position. i ask because i'm considering having a secondary relay that will cut out the starter relay when the engine is on, effectively preventing the (noob) driver from cranking the engine when it's already running.

now, my car is pretty loud so it would be hard to miss when the engine is running but this would sure come in handy for those quiet 'hybrid-type' cars that just whisper when the engine is running.
Texx, can you help on this one..?
 
Rob H

Rob H

Member +
The alternator charge light would be a good place to go as this only goes out if the engine is running, unless your alternator fails but that would be a one off. It is a good idea you have I have done it my self and I am sure many others will have too lol
 
dark_knight

dark_knight

Member +
alternator light feed

so the alternator light (at the dash) is NOT energized when the engine is running but remains energized at all other times..?
 
dac69er

dac69er

Super Moderator
may i ask why? if you are retarded enough to try and start the car while its running you shouldnt have a car!
 
Rob H

Rob H

Member +
yes the alternator light is only energized when the engine is off once the light goes out the power to it as gone till you stop the engine again.
 
Texx

Texx

Super Moderator
Rob H said:
yes the alternator light is only energized when the engine is off once the light goes out the power to it as gone till you stop the engine again.
Click to expand...

That's not exactly correct. The charging light is supplied +12v from the IG2 terminal of the ignition switch and grounded through the alternator at terminal A, so when the ignition is switched on the charging light illuminates. However, once the engine is running the alternator outputs charging voltage at terminal A. This results in +12v at both sides of the charging lamp and prevents the bulb from illuminating.

So +12v is always fed to the charging lamp when the ignition is on regardless whether the engine is running or not, it's the charging output of the alternator that cancels out the ground side of the bulb which turns it off.


You could however use the charging voltage output from the alternator to switch a normally closed relay and cut the ST2 output of the ignition switch. This would simply prevent the starter motor from being operated when the alternator charging voltage was at 9v or more. Unfortunately I've not got the time just now to pick out the correct wire for you, but you should be able to find it simply enough by probing the gauge unit multiplugs with a volt meter. The wire you want will be 0v (continuity to ground) with the engine OFF (both with ignition ON and OFF) and will have charging voltage (12.5v-14.5v) when the engine is running. By doing this though you may find that the charging lamp will glow dimly when the engine is running.


Seems a pointless exercise though.
 
dark_knight

dark_knight

Member +
push-to-start

well.. thank you all for all your responses but, i think i agree with Texx the most about using the alternator feed. and yes, i know it feels like a pointless exercise but right now, the missus is kinda using the car as a practice car for her driving experience vehicle and i've on several occasions watched her hang onto the ignition key long after the engine had fired to life and on two previous occasions, attempted cranking an engine that was already running.. :|
so yeah.. so that was food for thought on how to make this possible..

another thing that came to mind was the push-to-start upgrades that i've seen people doing. most times, the push-to-start button has to (for space constraints) be positioned around the centre console.. where it is susceptible to being pushed by touchy-feely noobs or kids riding in the car. i'm sure this mod would be an appreciated one in such instances.. :)
 
dac69er

dac69er

Super Moderator
no offense, but you sound like the managers we have at work. ask you to engineer out a problem at significant time and cost that would be solved by simply teaching the person how to do it properly.

seriously, just teach her. you wouldnt fit an automatic gearbox just because she struggled with the gears and clutch on her first few driving lessons would you?
 
dark_knight

dark_knight

Member +
lol dac69er.. no offense taken.. :) none at all.
like i said, i was just thinking about it. haven't actually planned on doing it but at times just knowing it's possible is enough.. and she's been trying to learn how to drive a stick for say 2 years now.. not much progress on that front so why not..? :)
but yeah, i like the approach of teaching the person themselves to avoid possible damage by not doing some things..
 
dac69er

dac69er

Super Moderator
another thing that is good to teach people is how a clutch works. in a normal car a clutch should pretty much last the life of the car if driven normally. but if you ride the clutch all the time it wears out. if you teach someone how a clutch works they understand that riding it all the time is wearing it out, and if they have half a brain cell, they will stop riding the clutch :)
 
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