OK,, this is going to be the first of many questions. So please be patient with me.

I've read the faq, and I didn't see this mentioned before.

I have a MS1 version 2.2 and I have built exactly like the instructions (because I built it like 3 years ago). I have GM water temp and air temp sensors. My N/A streetport will be breathing thru a weber 50mm ITB with 4 480cc injectors. I built errors add on card and want to use it with my un-modified CAS, but when I look at my original wiring harness pins 7,8,9,10,11,15 are all grounds. When I look at renn's modified wiring diagram, I see that only pins 8,9,10,11,15 are grounds. How do you modify pin 7 & 24 to be an input for the CAS?

What is pin 25 for on the modified wiring diagram?

Where does pin 27,29,31 connect to? (LEDs with pull up resistors? or somewhere on errors add on card?)

I hope somebody can help me.

 

on my board (which that 2nd diagram is of) - 27,29,31 connect to the 3 coils. That diagram is for a 3.0 board however, not a 2.2, and it's not using a daughtercard, it's using a modified CAS.

the rest of your questions, however, are over my head :P

 

The faq doesn't replace the original MS documentation, it only supplements it. To get a better understanding, go to the MS documentation site, and review the schematics for your board. That'll answer most of the questions you have below.

http://www.megamanual.com/v22manual/mtabcon.htm

As I said, the MS schematics shed some light on these questions. On the V2.2 board, all pins on the top row are grounded to the circuit board. On the V3.0 board, pins 3 thru 6 are all connected to solder pads to allow the user to pass other signals in/out of the MS. In either case the electrical load to ground isn't very large, 10A max in most cases, so it isn't critical that all available ground contacts are actually grounded. Pick your favourite 5, ground them, and you'll be fine. Pin 7 is not an input, but is actually the ground contact for the -ve CAS lead. It's not critical that you use pin 7, as on your board any pin in the top row will do. Pin 24 is the tach input, and is used to read the +ve CAS signal. No mods necessary for either pin on V3.0 or V2.2 board.

On your V2.2 board, pin 25 goes to the X11 pad on your board, which can be used to send or receive another signal. You could use it to pass an electric fan control signal out to a fan relay, or send an analog input (fuel pressure, EGT, etc) to the MS.

Pins 27, 29, and 31 in that sketch (x12, X13, X14 on your V2.2 board) are used to pass the 5v control signals out to your coil packs. Inside the MS box you need to run wires from the X12-X14 pads up to the LED's on the opposite end of the board. Pull-up resistors are needed as shown in my V3.0 build thread. Note that in the V3.0 build thread pins 25, 27, and 29 are used to send the coil control signals rather than 27, 29, 31 on the older schematic you posted. It makes no difference, so long as you build your harness to match.