Thread: Need help, great idea !

I would leave the computer out of it unless you must. You could always add a switch somewhere that turned your feature on/off.

Now to the actual question: I don't see why you couldn't do it. If you tap the line that lights the LED, you could have it also switch a relay; that relay will then close the same loop that your button does. This is only contigent on the LED line being able to carry enough current for the relay, which I would be shocked if it couldn't. You should also find out how much current is passing though the button, and get an approprietely rated relay.

if you're comfortably with the electronics, the hardest part is probably going to be taking apart your dash to tap the LED and button lines.

edit: Parting thought - The voltage in the LED line might not be enough for the relay. In that case, you'll need to use a transistor and a 12V line (this would also be the solution if the LED line can't carry the current).

The internet? There are a lot of good references and tutorials on line. Unfortunately I can't point to any off the top of my head, but I'm sure Google can find them for you. Then I'd say it's just a matter of trying out stuff to get a feel for it. Everything I described is pretty basic stuff, and if it didn't involve your car (which I'm sure you don't want to ***** up on ), I'd say it'd be a great first project.

Best method to learn about relays. Goto radioshack. Buy a clear one. Look at it. Put a 9v battery across the bottom two pins, that are differentl angled/shaped. See what happens. How I learned. ;-)

Also, a cheap book at borders, or even some good internet research can help you out with lights.

Basically what you want to do is this:

Those two "input pins" of the elay - the ones you hooked a relay up to - hook them up beteen a wire of the led. Like cut the wire, and put each end on those pins.

OK, now you need to pull out the switch. Extend both the wires running into your switch, but leave them connected. Hook both ends up to the relay, so when the relay turns on (what happened when you put a 9v battery to it) it makes the two pins you have the wires connected to click together. So it's like (from car)====(switch)=====(relay)

and for the LED it looks like this

(LED)===<------------------------- (to car)
-------(relay input pins)--

yeah easy peasy mate. the guys are pointing you in the right direction. but yeah i suspected that the LD line would not have enough power for a relay so would go with a simple trnasistor amplification circuit to feed the relay.

I am sure you can work it out pretty easy or someone will deign if for you if you ask nicely. You may even be able to find a cheap electronics kit that can be adapted.

basically the transistor will take the low current rise fromt he LED coming on and porvide a much more powerful output to swithc the relay on which will then be wired in parallel to your switch to act as though it is being pressed.

If you imaging the tranny has 3 legs (this is non sexual btw!!!), one is the input, one is the output and one is the input from the LED circuit to activate the output which is wired to the relay coil.

I apologise if i am repeating some stuff already said but could only do a wuick scan of the other posts as am in work. I would design it for you myslef but it has been about 10 years since i did anything like this and i don't want to blow your cars circuits!!! The tranny switch feed can just be spliced from one of the legs on the LED adn you jsut need a add a swich either on this lead, or the input or output from the transistor to turn it off.