OK, thanks for the heads up, I think I know what you're getting at.

I'll try and post a picture of the harness up. I've just been super busy lately and haven't had the time.

I do certainly appreciate the input though, thanks much  

PS: last post was edited, as I read what you had said earlier.

Just to clarify, the boot pin DOES NOT GET 12V.

Look, I'm gonna take the high road here and not turn this thread into a typical forum name calling mess.

However, I will state this for the record: As with all forums, there's a general rule that for every person who takes the time to ask a question, there are X number of people who have the same one.

Often times, people don't ask a question because they are self-conscious that they will attract a response just like the one you gave me.

The end result is that someone else doesn't learn from someone else's experience and the community as a whole suffers.

Now, if you want people on here to see you as someone who would hinder the learning process by discouraging people to post up their issues, then hey, it's up to you.

Alternatively, you can choose to use what you know to be seen as a stand-up guy who assists in the learning process.

They both require exactly the same amount of effort and I'm certain that you're more than capable of both options, so why risk being viewed as the former? Just remember, your responses reflect on you and your reputation and you only have one reputation.

Now, with that said, you likely have knowledge that could prove useful to myself and others, so thank you for pointing out my mistake, let's just keep things amicable from here on out, deal?

It's just the way prj is.  Hang around here long enough and you'll learn it's just the way he speaks. 

He knows these systems like the back of his hand, and I guess having people screw up basic things annoys him, after its repeated time and time again.  Crack on though, you'll be close. 

Just remember the ground pin is from ground, not +12V.  Just paranoid you weren't sure.

So just to get something clear here, (and bear in mind I need this explained in dummy speak lol) what exactly does grounding pin 24 to the side of the board do?

My understanding is that in order to enter bootmode, that pin needs a momentary 12v signal going through it.

Now, if I run a wire from the side of the board to pin 24 (i.e. a ground), how is that providing a 12V signal to the pin? Or is grounding to the outside of the board doing something else entirely?

Thanks nyet for that explanation, I've never bothered to find out what boot-mode actually is on that level.

For the dummy answer, think of a DC light bulb, like a normal brake light bulb in a car for example. You have to provide +12V to other lead and - (commonly known as ground) to the other lead. When both sides are connected, the voltage differential through positive and negative battery poles tries to balance out, electrons go for a swim and current passes through the bulb filament and it lights up. Every time electrons move around in a closed cirquit, their internal frictions on atom level produces heat. The bulb needs a certain amount of amperage to work and provides just the right amount of resistance to the cirquit so that most of that heat is radiated from the bulb and it doesn't burn through the wires and connectors etc. Now pretty much all DC components work with the same principle. Easy so far, right?

No if you would leave the bulb out of the middle and touch +12V and ground together, you get a short cirquit, which means you'll immediately try to balance the car's battery +12V and ground voltage differential through that little point. You'll get sparks and blow a fuse (heat through too much amperage through the fuse). If you didn't have fuse on the wire, You'd burn something else, usually a wire would heat up so much that it melts through its insulation, maybe then the bare hot copper wire is touching something like a floor mat or a seat cushion and sets that on fire.

This is basically what you are doing if you introduce +12V to somewhere it shouldn't go. Something will act as a fuse and burn as long as there is a connection, especially unwanted if that something happens to be an internal ecu component.

This was written from a laymans point. I've never studied electronics after basic classes in college. Couple of hours reading through wikipedia will sort You out.

Adam, Hopsis, and especially Neyt, thank you very much for the well thought out responses.

Nyet, I re-read your explanation and NOW I've got a rough idea of what you're trying to do to put the ECU into bootmode.

Also, as Hopsis said, I've never seen that explanation anywhere else on this site or otherwise either

I've found some reference materials on circuit design that I'm going to plow through in the next bit, I'll report back when I've covered some background reading.

Thanks