Clarification on "How to make and install your own Diy MS"
 

Just finished up making the changes needed to control spark with my MSI PCB3.0.

Just need a few things clarified:

On the 90-93 stock wiring diagram pin 1G is labeled as Green/White Pin 31 Ignitor and pin 2H labeled as Blue/white Pin 25 CAS.

Now the question is, on the DB37 diagram there are two wires for each of these colours, does this mean that I need to split each of these from the stock harness and run them to the respective pins on the DB37? That is to say Green/White to pins 31 & 29 and the Blue/White to pins 25 & 27. Or am I completely off base?

Next, the tach wire 2E is listed as being gray and I would assume it would go to pin 24 on the DB37 but the colour of that wire is listed as white while pin 26 is gray. But I though this was for TPS... I'm sure I'm missing something here.

This is on a '90 with the AFM in place to trigger the Fuel Pump and for the IAT (for now anyways). I don't have D19 installed right now but I was under the impression that this isn't an issue I'd just be missing some protection.

Also, on an entirely separate note. I'm wanting to run an external switch to jump the boot pins AND disable the spark output so that burning ignitor/coils won't be an issue but I lack the knowledge to do so. Any one wanna help out on that?http://www.boostedmiata.com/MS/harness_MS_pinouts.jpg

http://www.boostedmiata.com/MS/db37_MS_pinouts.jpg

I've told him to change this, but he's one lazy fuck!

look at it again.

HOLYSHIT! I must be going crazy...

tach is the thick sheilded white/gry wire. sometimes they come gry sometimes white. pin 24.

FP is fine with AFM in place.

wire pin 31 and 36 each through a toggle switch if you want. but you should only need to flash the firmware once to start. burning files isn't an issue.

Cool. Thanks for the help :)

I had the same question when I built my megasquirt. If i remember correctly, I used pin 25 for cas and 31 for one of the ignitors.

If you're still interested in doing the external switch i can help guide you in the right direction. You could actually do it with one switch. I only have the switch for my coils though. That was back when i had for for fuel as well.

uh ohh...
have one blue/white and one green/white without use. is that correct.?

Pin 27 and 29 are optional. You can use them for like knock input, launch, EBC, w/e.
The IAC-- I/Os on the MS are connected to these DB37 pins:

IAC1A -DB37 pin 25
IAC1B -DB37 pin 27 Blu/Wht
IAC2A -DB37 pin 29 Grn/Wht
IAC2B -DB37 pin 31

Fired it up yesterday. Thanks for the help, guys. :)


I really expected a pain in the ass couple of hours of flashing the firmware a few times, thus my desire for the switch, but with the exception of MSII downloader corrupting the firmware once it went smooth as silk.