Need help with MS (shocking... lol)
 

ok, so i had my MS assembled... then today i went to take off the "unnecessary" components to match per brainiac's picture...
now, i don't get no coolant reading off the megastim.
also, should the 3 LEDs light up when it connects?
My RPM doesn't show up either. when i move the rpm knob on the megastim, it won't work. all the other ones will work no problem.
To sumarize...
No RPM and no COOLANT readings on MegaStim...
No LED activity.
(not i already tested flipping the LEDs to no avail).
thanks guys.

If you had built it with everything there was no reason to remove anything. I just leave off certain circuits most never use to make the build faster/easier.

if you're getting no coolant reading, do you have R4 removed?

RPMs will not show up on a MegaStim, it cannot simulate the miata CAS readings.

R7 is removed, R4 is installed.

your thread talks about R7... i'm gonna re-install it and see what happens.

thats what i meant. what year miata is this for, what type of harness?

ok, R7 is back in and coolant temps are now showing.
still curious about the LEDs.

it's a '91, standalone with MS-I

The two outer LEDs represent Spark A and Spark B, they will not light up without an RPM signal, you will not get an RPM reading using the meagstim, you must use the JimStim.

leave both r4 and r7 installed for a standalone install.

and the inner LED? i checked your threads and there is no info as to what each LED means. how do i know if i installed them in correctly?

The outer LED drivers get hijacked to drive the two spark outputs. So the LEDs themselves no longer serve a useful purpose. Incidentally, see here: https://www.miataturbo.net/forum/t33964/

The middle LED, by default, indicates when the MS is in warmup mode. On engines with 3 or 4 ignition channels, it is SparkC. It can also be hijacked for use as "Output 4", a general-purpose output.

would the middle LED be connected to his fans mod? (if thats installed)

i cant remember if it was the middle LED that only goes on when the fans go on. i originally panicked when it went out during my build.

Could be. I think D18 is the default pin for fan control, though you can use any of the general-purpose outputs if Out4 is already taken.

ok, now building the harness. i got per the wiring diagram posted by "joe perez" to run the IGN (shielded) wire to pin 36 of the DB-37, but can't figure what to do with pin 24, but if i follow the pic closely (posted by braineack) i get the IGN shielded wire to pin 24 and the brown to pin 36

n/m that. i just went with the pic. lol.
Last question for the wiring... the "clutch" green/white wire... does it have to be plugged in? and what does it do exactly?

Don't go implying that I told anybody where to put that damn shielded wire. :D I put all of mine directly into the trash can.

(The shielded wire is not necessary with anything other than a VR sensor, and it's too damn bulky and hard to work with.)

The clutch wire is needed only if your MS has been internally modified to support Launch Control. Internally, it would be connected to J11, however what pin on the DB-37 that would correspond to is up to whoever did the mod.

ok, all the wiring is done, only one question remains...
which wire carries the stock O2 sensor signal? i'm doing the pnp harness, and everything else checks out, except the O2 signal wire, which i can't find where to plug it to.

On your '91, the factor O2 sensor comes in on the red/blue wire at position 2N which is sheathed in a black sleeve.

ok... so i finished doing that, and i go and install it... smoke comes out and one of the lines gets fried. it's the thick one that comes out of the midle of Q12 & Q9. Q9 has mica insulator, Q12 does not. should it have an insulator?
and also, the MS no longer connects to MegaTune...

Off the top of my head, I can't recall whether the tab of the TIP125 is electrically connected to the collector, but if it is, you have shorted V12 to ground.

insulator is now on Q12 & Q9, but ms still won't connect. did i fry the CPU?