Push Start Button, electrical diagram - check please Options

[pittfirefighter]

Ok so i got my button in! but i need someone to verify that this will work...

Red box is a 12V source that gives 9-14V when the car is on and Running (W on ecu, 5th pin on 2nd harness)



push it once with clutch in should start the car... push it again should turn the car off

push switch is a momentary switch - it does not stay locked in position

all relays are in their open positions

This post has been edited by pittfirefighter: Dec 27, 2009 - 10:18 PM

[BloodyStupidDave...]

Ok so i got my button in! but i need someone to verify that this will work...

Red box is a 12V source that gives 9-14V when the car is on and Running (W on ecu, 5th pin on 2nd harness)



push it once with clutch in should start the car... push it again should turn the car off

push switch is a momentary switch - it does not stay locked in position

all relays are in their open positions

No, it's not quite right. You have the ACC and IGN lines tied together at the top and once the button is pressed the first time, they are additionally tied to the battery. Perhaps some diodes? Additionally, you probably want some diodes across the relay coils to prevent back-emf and probably use latching relays rather than have the coils always energised for the latching function.

Are you assuming that when the battery is disconnected from IGN and ACC, pin 5 will go to ground? Oterwise, I can't tell how a second press kills the car.

For safety's sake, I'd suggest either two presses within one second should be needed to turn the car on/off or alternatively a 1 second long press.

One final consideration - if you don't already have one, fit an immobiliser and position the coil wherever you are going to put your keys (eg next to a cubby hole). They you can just throw the keys in the cubby hole when you jump in the car, but without the keys in the cubby hole someone else won't be able to start and steal your car.

[pittfirefighter]

Ok so i got my button in! but i need someone to verify that this will work...

Red box is a 12V source that gives 9-14V when the car is on and Running (W on ecu, 5th pin on 2nd harness)



push it once with clutch in should start the car... push it again should turn the car off

push switch is a momentary switch - it does not stay locked in position

all relays are in their open positions

1. No, it's not quite right. You have the ACC and IGN lines tied together at the top and once the button is pressed the first time, they are additionally tied to the battery. Perhaps some diodes? Additionally, you probably want some diodes across the relay coils to prevent back-emf and probably use latching relays rather than have the coils always energised for the latching function.

2. Are you assuming that when the battery is disconnected from IGN and ACC, pin 5 will go to ground? Oterwise, I can't tell how a second press kills the car.

3. For safety's sake, I'd suggest either two presses within one second should be needed to turn the car on/off or alternatively a 1 second long press.

4. One final consideration - if you don't already have one, fit an immobiliser and position the coil wherever you are going to put your keys (eg next to a cubby hole). They you can just throw the keys in the cubby hole when you jump in the car, but without the keys in the cubby hole someone else won't be able to start and steal your car.

1. ACC and IGN should be tied together (IGN is not START, it is live when the key is usually at ON) and therefore taken straight to battery when the car is running... diodes are a good suggestion - not quite sure how latching relays work...

2. no pin 5 will not ground - if it was to ground, then the battery would short circuit... pin 5 is open creating an open circuit - open circuit would create no power flow therefore IGN and ACC don't get any power and the car shuts off

3. that will be determined depending on how well the car starts

4. already have an immobiliser worked out... i want to get the starting function down first before adding that in