Engine Start Button Wiring

[alarsuel]

I am working on a juke with a car theme and I am to the point of wiring my start button to control cpu power.  gryhnd started to walk me through it via pm (thanks!), but now that I have the specific parts in I was hoping to get his input as well as others here.  I think it might be good to have for others reference, too.  Here is my switch (off of ebay, of course):









Here is my power supply (boo, old Dell stuff):


Here is the power suplly connection to the mobo:


This is what currently switches the power for the cpu:



  Sorry for the blurry last shot.  My macro skills suck.

The wiring currently is as follows: From the mobo to the switch there are 3 pairs of wires.  Green and black to the switch, a separate green and orange to the led next to the switch, and a red and black to the 2nd led.  There is also a yellow wire which goes from one one port to another on the mobo connector.

The wiring instructions that came with the switch call for the following: positive parking light to socket #1.  Ground to socket #2.  Ignition to socket #3.  Starter wire to socket #4.

I am familiar with home wiring so I don't have any problems making the connections and splicing in wire to give me a longer run, but I'm not that familiar with computer wiring and I'm not sure which wire from the mobo would be equivalent to the car wiring.  Anyone have an idea?  Also does it matter what wire I use to splice?  What guage?  I have some cat5 laying around if that would work.  I assume it should be solid core so no speaker wire?  Thanks!

Aaron

[Donkbaca]

doesn't matter if its solid core or stranded. All you need to start the computer is to make momentary contact between the red and green wire that is connected to the switch.  Try it out.  cut the wires off the switch and brush them up against each other, then the computer will turn on.

Not sure about that engine button. What kind of a switch is it?  I suspect that none of the contacts you mentioned is a momentary one, but I don't know anything about car wiring.  If that is the case, you can't use that switch

[alarsuel]

The green and black wires from the switch are, in fact, stranded.  I cut and striped them and as you and gryhnd indicated touching them together powers the cpu.  Touching them again cuts the power.  Not sure how to check if the engine button is momentary, but I know that others have gotten engine start buttons to switch power to cpu's.

Not sure if this means anything to anyone, but the wiring instructions also say:
Connect the Ignition wire to NO 3 -
You have access to Ignition wires, find the "ON" wire. That wire will only have power when the key is in the "ON" position.

*By wiring this way the key has to be in the ON position for the Starter Button to work, in addition the start position on your ignition will no longer work, in other words by wiring it this way you will have to put the key in the ON Position and press the starter button.

(Terrible grammar taken from instructions)

[gryhnd]

Engine start push buttons are in fact momentary. They simply replace the monetary of a normal ignition switch.

Mine was a bit different that alarsuel's in that the button actually fires off a relay box (probably b/c mine also has built in LEDs), but the concept is the same.  What you want to do is get your handy multimeter out, set it so that you can read continuity (one of the ones with an ohm symbol). When you touch your two probe leads together the meter should give you a reading.  Work your way around the connection options (probably "NO" is what you want) and when you get to the one that gives a reading ONLY when the button is depressed, that's the two you hook your MoBo wires to.

[alarsuel]

Thanks for the reply.  Let me repeat so that I'm sure I know what I'm doing.

Touch my two leads from my probe together to make sure I'm getting a reading.

Use the two probes to go around test the different terminals to find a pair that only give a reading when the button is pressed.

1 of these 2 is probably "ON".

Connect one of my switch wires to each of these terminals.

Doesn't matter which wire to which terminal.

Is that correct?

[gryhnd]

Is that correct?

(btw, it's N.O. for Normally Open...one wire will be common (-) to all which is where you put one probe, and then you move around the other options with the second probe)

[alarsuel]

Worked great, thanks!  Wires are connected to terminals 3 and 4 and the button now turns the cpu on with a press.  Holding it for a bit longer will cut the power.  Only hiccup is that the button has an led in it which should light up when powered.  Could it really be as easy as clipping the 2 wires from one of the green leds that was by the old switch and connecting them to the other two terminals on the engine start button?  Those terminals are "positive parking light" and ground.  Possibly green to the ground and orange to the light?

[gryhnd]

Only hiccup is that the button has an led in it which should light up when powered.  Could it really be as easy as clipping the 2 wires from one of the green leds that was by the old switch and connecting them to the other two terminals on the engine start button?

Doubtful, but I can't say for certain. I think the LEDs on the Dell are 5V, whereas cars are all 12V.  You could try and see what happens...maybe use a 5V wallwart you have laying around if  you do, to test the LED. I think you'll find though the LED doesn't light or is very dim.

So then what you do next is up to you: wire to the PSU 12v for LED lit when the PC is on. Or a 12V wallwart plugged in to the mains for the LED lit all the time.

[alarsuel]

You were correct.  No juice from 5v.  I tried both wires into both remaining connections and got nothing.  I think option "B" is best.  I have a 12V wallwart laying around I don't mind cutting up.  I'll wire from wallwart to light and plug it into a smart strip.  That way it will give the appearance that it is only lit when the computer is running.  Specs on the wallwart

INPUT: 120V AC 60Hz 0.3A
OUTPUT: 12V DC 750mA

Seems ok, yeah?  Since we assume car leds are 12V, I shouldn't need a resistor...  Positive wire to "positive parking light" terminal and negative wire to "ground"?  Seems a little weird to use the ground terminal without a ground wire, but those are the only terminals left.

[gryhnd]

Seems ok, yeah?  Since we assume car leds are 12V, I shouldn't need a resistor...  Positive wire to "positive parking light" terminal and negative wire to "ground"?  Seems a little weird to use the ground terminal without a ground wire, but those are the only terminals left.

Yes on all counts. Caveat about "assume" of course.

[alarsuel]

Worked perfectly... Thanks for your help.