MSefi.com read only forum (Jan.15,2018)

I am building an ms1 v3 and I am a little confused. I have a holley throttle body with a stepper iac. The directions say...

22. Now you need to make a decision on the first 'optional' component: if you are going to use an IAC stepper motor with MegaSquirt-II, you must install a jumper from the hole marked S12C to the hole marked JS9 (+12C). These are on the bottom side of the board, on the DB9 side of the processor. DO NOT INSTALL THIS JUMPER FOR NON-MegaSquirt-II APPLICATIONS - IT WILL DESTROY THE PROCESSOR!!

If you are going to use a stepper style IAC (such as the GM IAC), you need to connect jumpers to bring the controller signals out to the DB37:

Connect (1A)JS0 (under the processor socket) to IAC1A (near the DB37 connector) - this brings out IAC1A on DB37 pin #25
Connect (1B)JS1 (under the processor socket) to IAC1B (near the DB37 connector) - this brings out IAC1B on DB37 pin #27
Connect (2A)JS2 (under the processor socket) to IAC2A (near the DB37 connector) - this brings out IAC2A on DB37 pin #29
Connect (2B)JS3 (under the processor socket) to IAC2B (near the DB37 connector) - this brings out IAC2B on DB37 pin #31

So for part 22. I don't jump s12 to js9, because that is for msII. But I can go ahead and install the jumpers below that for my ms 1? I just want to be sure I'm reading it right.

Rusty,

You cannot use a stepper motor IAC with MS-I (so don't install any of the jumpers, they won't work). If you want to use a stepper IAC, you MUST upgrade to MS-II (and install the jumpers).

Lance.

Well that's sucks.

Hi If i have read upgrades correctly you can remove the 40 pin prossesor that came with the ms1 and install the ms2 in its place and make some other mods. some one else out there may know more on this?

Correct - it's a simple as that. The stepper motor driver IC is on the MS2 daughter board. The V3 board is the same.

If you do decide to configure it for a stepper motor and MS2 do not power it up with an MS1 installed. The 12v feed for the stepper chip on MS2 will damage MS1.