start/stop button in injected car, where to start?

[lunarhighway]

startbutton revisited


in my previous car a had a start button and initially i had planned a stop button as well but never got round to completeing it.

i notice that i have developed the good habbit of shutting off the engine at every stop light and the button that was located in front of the shifter was a great help. i recently disconnected the button as it used the power for the 12v socket wich i needed for a GPS, and i notic reaching fot the key at every stop is quite a distraction

my next car obviously doensn't come with such handy features, so i'm going to try to refit it. problem is that electronicly this car is a great deal more complex than what i had,

the kadett was a 1987 carbed model while the vectra is from 1995 throttle body injected model. still not very advanced by todays standards but i'm not going to start cutting wires without knowing where they go and than have all sorts of lights come on etc...

the start button shouldn't be to hard, as it's just a parallel switch to the ignition key
but the stop button had and has me scratiching my head. i want to shut of the engine but nothing else. on the old car stopping the ignition was enough , but on this one i have the injectors and he chip to worry about.

can anyone give me some pointers to how all these systems depend on eachother and what i should be looking for to stop the engine.. can i somehow shut of the power going to the ignition or would that make the car mad?

ultimately i'd want a single button switch that with the key is in the ignition and turned to on, will stat the engine when pressed and will stop it when pressed again.
however initially a basic two button system would be fine.

[GasSavers_RoadWarrior]

I'd shut off the fuel, not the ignition.

[lunarhighway]

makes sense, however HOW do i do this?, on the old car it was just cut the ignition and everything stopped, but here i have an injector and an electric fuel pump to worry about... good thing (?) is i have only one injector to worry about.

i have to take a closer look under the hood for lack of a propper scematic so far, but is it possible all these things are controlled buy the same module that controles the ignition? what would be the easiest and safest way to stop the engine but nothing else? cut the power to the ignition module? i assume that also controles the injector?

i know some basic things about cars i learned trough messing with the kadett, but this injection thing is new to me so i'm a little unsure where to start

[GasSavers_RoadWarrior]

If it's a system that returns fuel to the tank, just interrupt power to the injector.

[Lug_Nut]

I'm presuming there is still a spark distributor and a single coil? Interrupt the electrical power on the primary (low voltage) side of the central coil.
Individual coils? Sorry, can't help.
Cutting the electrical power to the high pressure fuel pump may not reduce the pressure enough to assure engine rotation cessation. Many cars have two pumps. The low pressure pump to keep the main one from cavitating may just be enough to keep the TBI functional.
If there is a separate fuel shut off solenoid, then cutting the power to that electrically operated valve will immediately starve the engine.

[cfg83]

lunarhighway -

This may not work for you, but Skewbe found a fuse on the Saturn S-Series labeled "inj" for injector in the engine bay fuse panel :

The fuse labeled "inj" is a 10 Amp fuse on the second row of this picture ... :


... Corresponds to position "B7" in my artificial grid :


Skewbe setup a momentary button to disable the connection at the fuse. Press the button while moving in neutral and the engine goes dead while the rest of the car works as normal. This mod is on my (infinitely long) to-do list.

*If* you have a fuse for the injectors (and/or the fuel pump?!?!?!?), then maybe you can apply a similar solution.

CarloSW2

[lunarhighway]

cfg83

thanks! i haden't thought of that! i'll look into that option...might make things easier than i expected! would the car complain about this? any warning lights or the ecu doing strange things?

[cfg83]

lunarhighway -

Originally Posted by lunarhighway

cfg83

thanks! i haden't thought of that! i'll look into that option...might make things easier than i expected! would the car complain about this? any warning lights or the ecu doing strange things?

I think it would depend on the car. Here is what I would do if I were you :

1 - Find the fuse (if it exists)
2 - Make sure you have a spare fuse just in case
3 - Idle the car in neutral in the driveway
4 - Pull the fuse out
5 - Watch what happens (engine should stall)
6 - Look for warning lights on the dash

Let me look around for a moment ... rummage rummage rummage ... here it is :

SG Shenanigans

Originally Posted by skewbe

For the kill switch, I wired up a blown fuse actually to plug into the fuse carlosw2 indicated, then cut a little of the fuse box covers edge so the leads could escape unharmed.



more info:
If the inline fuse burns out, just unplug the whole kill switch circuit and plug in a fuse till you can fix it. No kill switch till then, but the car will run

I didn't have a burnt out fuse, so I popped one on the battery with a jumper. whee.

This technique is sure to work on a lot of different cars.

Digital odometer and EO gliding
http://www.gassavers.org/showpost.ph...00&postcount=6

It varies somewhat for each model. Here is what I put in my metro (and the rest of the thread us useful to):
http://www.gassavers.org/showthread....1008&page=2#34

I used the same switch in my saturn, but just put it in line with the FI (presumably Fuel Injection) fuse and didn't cut any existing wires.

An ignition kill switch is also popular.

It is pretty easy given some basic electrical skills.

coasting
http://www.gassavers.org/showpost.ph...9&postcount=30

I just did it on our 97 sw2, I found an "inj" fuse under the hood and put a micro switch inline with it and glued the switch to the auto shifter (index finger friendly position), bada bing.

(ok technically an injector kill switch, even better)

CarloSW2

[lunarhighway]

thanks for the summary that will save me a lot of digging.

i've been sketching up some ideas on how i could both start and stop the engine with the same push button, as it would have to do two totally different things.

the answer is fairly simple, have the button remember what it did last and than have it do the other thing next time. but this might create some problems when the car doesn't do what it's tolled (not start the first time or restart on vapours)

here's a scematic i drew up... i didn't use the correct symbols wich may offend the very people who may be intrested enough to look at it , but i didn't want to look it all up again for now. the wite boxes are either make or break relais and the green area are just two leds that show the status of the system....

the secematic shows a bunch of relays with perhaps are better substituted by transistors or maybe even a chip, but that would soon go over my curent knowlege. perhaps theres a much more simple way that i fail to see...i tend to overthink things

if anyone's interested i'm willing to explain how i think this would work.


b is the push button and sx1 and 2 go to relays that power the starter or shut down the injector

[Lug_Nut]

the answer is fairly simple,...

...if you're into solutions in search of a problem...
My opinion is it's far more complex, with a multitude of possible failure points, than accomplishing the same function with a pair of momentary interrupt switches.

What is the function of diodes lg and lr?
What are the green and red rectangles in line with the lg and lr diodes?
What is to prevent the normally closed relay contact sl from shorting since line is connected to 12V and load is connected to ground through the lr diode?
Would "latching", (parallel wiring the coil input with the load output), not simplify things by reducing the overly excessive number of unneeded relays? A pair of relays, triggered by a pushbutton and then self maintaining, would reduce the number needed to two.
But, since the start circuit is only needed momentarily (during starter cranking), and the stop function is only needed momentarily (until rotation ceases), why bother with relays maintaining continuity at all when two momentary switches will suffice?