I'm in the process of putting together a spreadsheet for all the wires on a MS-II, V3 pcb for a 99+ miata. I'm pretty sure it is compatible with an MS-I

Anyway, before it's done, I have a couple questions:
MS # MS Net MS Function Abe's Function OEM/MS/Both

1 GND Both
2 GND Both
3 SPR1 Spare 1
4 SPR2 Spare 2
5 SPR3 Spare 3
6 SPR4 Spare 4
7 GND Both
8 GND Both
9 GND Both
10 GND Both
11 GND Both
12 GND Both
13 GND Both
14 GND Both
15 GND Both
16 GND Both
17 GND Both
18 GND Both
19 GND Both
20 MAT Manifold Absolute Temperature GM AIT MS
21 CLT Coolant Temp Sensor OEM CLT ?
22 TPS Throttle Position Sensor OEM TPS ?
23 O2 WideBand O2 Sensors LC-1 MS
24 TachIn Timing Signal In Crank/Cam Trigger ?
25 IAC1A Idle Air Control Coil 1 A
26 Vref Sensor Voltage Reference Output? Sensor Voltage Reference Output? MS, AIT?
27 IAC1B Idle Air Control Coil 1 B
28 12 RAW ?
29 IAC2A Idle Air Control Coil 2 A
30 IDL ?
31 IAC2B Idle Air Control Coil 2 B
32 INJ-1 Fuel Injector Channel 1 Out Injector 1 & 4
33 INJ-1 Fuel Injector Channel 1 Out Injector 1 & 4
34 INJ-2 Fuel Injector Channel 2 Out Injector 2 & 3
35 INJ-2 Fuel Injector Channel 2 Out Injector 2 & 3
36 IGN Ignition Out Ignition 1 & 4?
37 FP1 Fuel Pump Relay Out Fuel Pump Relay


Basically, there's a few things I don't know what they do.
1)IDL I'm assuming is where my idle valve comes out on

2)12 RAW I have no idea what it's for (12V switched in?)

3)VRef I guess I run to all the sensors, in place of the OEM line that does the same thing - my question is, should I just tie them together? If the OEM ECU needs to see the AIT sensor, is it ok to tie the two computer's sensor grounds together? I might just jumper the AIT with a resistor in the harness.

4)Things like coolant temp, TPS, and cam/crank signals... Do I want the OEM ECU to see those?


And, just as a taste, here's my chart I'm working on, I'll post a cleaned up version in excel format when I'm happy with it:


OEM Color MS Color L # Function Section/Notes Pin/page ref
I/R A 1 Const. Power (80A Main, 20A BTN1 fuse and 10A Room Fuse)
W/R B 1 Switched Power In (From Main Relay, to Cam & Crank sens, Solenoids, Fuel Pump relay and Injectors)
* C 1 (none)
G/W D 1 Data Link Connector U 19, 20
W/L E 1 Instrument Cluster C-a 30
G F 1 Brake Switch F-2 31
BR G 1 PSP Switch
G/R H 1 Const. Power (30A Fuel Inj Fuse, feeds Main Relay)
L/W I 1 Condenser Fan Relay G 26
* J 1 (none)
*<V/G> K 1 Transmission Control Module H-1 32
BR/Y L 1 Data Link Connector U 21
* M 1 (none)
*<P/B> N 1 Transmission Control Module H-1 33
GY/R O 1 Generator A 6
LG/B P 1 Refrigerant Pressure Switch G 24
BR/R Q 1 Insrument Cluser C-b 16
R/G R 1 Cooling Fan Relay B-3 22
L/B S 1 A/C Relay G 25
GY T 1 Generator A 5
V/Y U 1 Oxygen Sensor, Front, Heater Return Line
V<*> V 1 Neutral Switch 1
R/G A 2 FTP Sensor (A, Signal)
P/L B 2 Air Intake Temperature Sensor Signal
L C 2 Oxygen Sensor, Front, Signal (shielded)
W/B D 2 Instrument Cluster C-1 23
R/L E 2 Engine Coolant Temperature Sensor
W F 2 Knock Sensor w/Shield Wire
* G 2 (none)
GY/L H 2 Camshaft Position Sensor (B, Signal)
LG/R I 2 Reference Voltage (TPS-A, EGR-boost-C, FTP-C) + Transmission Control Module H-1 35
GY/R J 2 Crankshaft Position Sensor (B, Signal)
G/O K 2 Data Link Con, Trans Ctrl Mod, Inst. Clust 12, 34, 11
LG/B L 2 Mass Air Flow Sensor (B, Signal) U, H-1, C-a
V M 2 EGR Valve
W/G N 2 EGR Valve
P/B O 2 EGR Valve
P P 2 EGR Valve
B/Y A 3 Chasis GND (?) 5
B/Y B 3 Chasis GND (?) 5
B/L C 3 Chasis GND (?) 5
* D 3 (none)
G/B E 3 Throttle Position Sensor (C, signal) + Transmissions Control Module H-1 14
B/R F 3 Sensor Ground (AIT, CLT, O2, TPS, EGR Boost, FTP)
BR/Y G 3 Ignition Coil No. 1 (D)
BR H 3 Ignition Coil No. 2 (D)
BR/W I 3 Cruise Control Module + Clutch Switch Q 36( + 3)
R J 3 Oxygen Sensor, Front, Signal (shielded)
BR/B K 3 Insrument Cluster C-a 15
BR/R L 3 Purge solendoid vavle
O M 3 IAC Solenoid Valve
LG N 3 Fuel Pump Relay B-2 27
V/R O 3 IAC Solenoid Valve
* P 3 (none)
W/L Q 3 VICS Solenoid Valve
* R 3 (none)
GY S 3 EGB Boost Sensor (B, Signal)
GY/B T 3 EGR Boost sensor solendoid vavle
L/O U 3 CDCV (then Main relay) B-1a 10
R/Y V 3 Oxygen Sensor, Rear, Heater Return Line
Y/B W 3 Fuel Injector No. 1
V/G X 3 Fuel Injector No. 2
Y/R Y 3 Fuel Injector No. 3
Y/G Z 3 Fuel Injector No. 4

 

Abe, to save your formatting, you might want to build a spreadsheet in excel (or equivalent), take screenshots and host them, then post your chart as a .jpg.

When you're done, I'll sticky the thread or somehow incorporate it in the MS DIY Build thread.

 

http://www.madracki.com/miata/images/wiring/99sys.pdf

Guess you know this one...

 

Yup. That's your PWM idle valve. Goes to Q4, which you modded, right?

The main +12 input.

You can use that for the TPS pullup, but the other sensors (temperature, crank/cam, etc) are pulled up internally on the board.

It'll need IAT for sure, the rest depends on what it's doing, I suppose.


What's with Coil 1A, Coil 1B, Coil 2A, Coil 2B. You running four coils?

 

Yeah - I was thinking it could go in there. I'm close to done, but not yet. I want to add as many of the MS pins on top of that chart, to make one (they are on my end) so when* I make a harness, I know whether to go straight across, to splice, or to take the line.


Now they are. :-) What I'm wondering is why the hell does the TPS need a pullup? Is it somehow a digital device?? Cause a potentiometer shouldn't need a pullup, if it does, you'd better get the right one it would seem.

Anyway, a number of sensors all through the car have a "v-ref" line, since there's only one comming out of the OEM ECU, I could just steal it and attach it to the MS. I was debating parallelizing them, but now I think I'll just cut the OEM one.

No reason to give up factory cruise till I need to. But I have no idea what it uses, or how it works. Maybe it puts out a voltage that defines throttle position, makeing the "cruise control module" just a variable throttle plate. But I don't think the ECU watches all the "accel/decell/resume" functions from my control stock, so maybe it's a simple enable/disable for an intelligent box.

Either way, something has to see the speedometer, and I never saw that input anywhere.

Nope. That's stepper motor idle control. I labeled things what the MS calls them, and I have another collom (mostly empty) for what I'm doing with those pins - which is why I'm asking all the questions. I think I'll make as good as cable as I can, and initially just let the MS tap into the cam/crank sensors and see if it sees the engine run.

After that it's just figure out why I get ZERO fuel while cranking, and I'm good.


*Supposed to be in 5 minutes after I eat this Spicey Chicken Burrito.

 

Because the ECU, the MS, and every other civilized device are expecting to see a variable voltage on the TPS input, not a variable resistance. The 1.6 AFM is the same way- internally it's a potentiometer, but it has a bias voltage applied across it so it outputs a voltage. Here's how the circuit works:

It's a variable voltage divider. So you put +5ref on one side, GND on the other, and as the wiper moves across it the voltage at the wiper changes. I just measured mine and it's about 6.7k, so the power dissipation through it is only about 4mW.

Yeah, I sometimes forget that the NBs have more sensors. According to the '00 wiring diagram, that line (LG/R at 2I) also goes to the "EGR Boost Sensor" and the "FTP Sensor"

I have absolutely no idea what either of those do, but I'm guessing that apart from a CEL you can live without them.

I don't think you'll have to give it up. Page Z-74 of the FSM indicates that it has no connection to the ECU at all. But you raise an interesting secondary point- who knows what's going to stop working in the instrument panel when the ECU comes out- there are several interconnections and none of them are clearly documented.

BTW, you do have the factory wiring diagram, right?

Gotcha. The usual custom is to use pin 36 (IGN) for Spark A, and pin 31 (IAC2B) for Spark B.

For the inputs, the usual convention is to put the crank sensor (CKP) on pin 24 (TachIn) and the cam sensor (CMP) on pin 25 (IAC1A). I'm still not sure how you're gonna deal with the NB sensors in software, but I'm looking forward to seeing it.

 

Sure, except you end up with this:


Which, ok, works. But you're going to get a totaly different slope, lose dynamic range, and all around blow little tiny monkies. At least, if I'm seeing it right. This is what I get:

I added a helpful guide on the right side for those who don't speak schematic.

Am I totally missing something here? It seems to me, no matter what you guess, you're going to be totally changing the output of the sensor. Putting a resistor equal to the pot's total works at one end, and none works at the other (but it will give you a dead short on full throttle). Something in the middle will... Kinda work. In places.

Ah, well, there goes my next question. PC Load Letter? I have no idea what an FTP sensor is. The boost sensor may very well have to do with barometric correction, something I will dig into once I'm running. Honestly, I was hoping to save the $28 and use it originally.


According to the wiring diagram I saw, there was one pin that went "to" the cruise control module. I have no idea if it's an in, an out, or just there to keep someone in japan with a job wiring it up.

I'm hoping it's essentially a stand alone device. BEGONE! evil oem cpu demon.

I am concerned. There are only a few lines to the dash. I doubt it's a serial bus (though if it is, look out world, here I come! CANbus to the rescue!), so it doesn't talk MUCH. I assume at least one is the CEL.

Roger Wilco, no boat rocking for me

Ah, good, that was my last issue, not being sure where to put cam or crank.

I have to see what the rest of the sensors are. Really, things like EGR I can drop. I guess it would suck if the EGT is full time open, does anyone know? And FPT... All I can think is Fuel Pressure, somehow, but you got me.


Anyway, thanks, that really helps. Now I think I can make my harness. You know, after I hook up my ignition outs. :-P

 

:bowr ofl:

That diagram is priceless!!

I wish I had something to add to your thread, but I don't. Not familiar with NBs..

 

No. Why would you? There is no internal pullup on the TPS line- it comes in at pin 22, transits a resistor and couple of caps (noise filter) and then goes into the CPU at pin 26 (AD3). Nothing in the circuit would cause the pullup that you've shown on the wiper line.

EDIT: Wait a sec, I think I see what you mean. The flag I marked as"TPS" was the TPS input terminal on the MS. The potentiometer I illustrated was the actual TPS itself.

Google to the rescue! FTP = Fuel Tank Pressure. Another one of those damn sensors whose sole job in life is to throw a CEL! Frak it.

Google to the rescue again. EGR Boost Sensor is a MAP sensor that's on the EGR line, to verify that the system is operating. Yet another sensor whose sole purpose is to throw a CEL.

I'm starting to wonder how much of your car (by weight) is dedicated to the sole task of helping you to fail a smog check...

Oh, you mean ECU pin 3I? It's just the clutch switch. That line goes to both places. At worst you might need a pullup- use a voltmeter to find out.


And with that I'm signing off for the next two weeks. Got a 6am flight to Florida, where I will chill with the family and try not to think about engine management.

 

Ah, well, I think I figured it out - it sounded to me - wrongly - that you were suggesting I internally pull up the TPS. Now I see you and I were saying the same thing. And it makes perfect sense. Or we're both totally wrong in the same way. Anyway, I feel better. And a lot more sober than when I drew that pic.

Ah, fuel something, I knew it. Yeah, that's one that can go. Maybe I'll make a dashlight for it. :-P
The EGR is kinda annoying. What's weird, there IS a boost sensor under the hood, just sitting there, and I didn't see a reference to it on the wiring diagram. A cute, perfect little sensor, ripe for the using. I wonder where it goes? Maybe, somehow, it IS the sensor you're talking about, and the port I saw is a absolute reference itself (i.e. it's a true boost sensor, NOT an absolute pressure sensor).


The number of times you make me regret not just RTFM'ing is truely stunning. Look at all this stuff I could do for myself. You know, if I were you.

Sigh, then telling you thanks and have a good one is pretty pointless. :-)

 

Here's my It's 5:20 am, my feet are cold and I didn't format it "as installed" parallel wiring adapter. I hope it makes sense to you, it did to me.

As I mentioned in other threads, it seems (with an MS-II) the only thing worth keeping the stock computer for is the alternator, and that's a ten dollar fix, if I can't get the MS to do it itself.

 

Not sure what thread to put this in, eventually I'll have to compile it. I'll copy it in the DIY thread, I think.

Since the whole wiring loom thing didn't work, i.e. no battery charging, and I wasn't going to invest time giving the OEM ECU one more signal at a time till it decided to play ball and run the altenator, I bought one of those MOPAR regulators. So, yeah, I'm out ~$25, but I think that was the last thing keeping me needing a OEM ECU.

Notes for posperity:
Ok, picked one up - had a little trouble with it for a bit, eventually proved to myselve stuff was working by putting at 20 turn pot between power and the signal in line to the altenator, and finding out that ~0.980 volts got it charging to around 14.3V.

Anyway, armed with said knowledge, I found out the correct wiring for this. Thought I'd note it here for posperity:
To wire up NAPA part number:
New Voltage Reg Napa online MPEVR38SB $15.29 "VR38SB"
Connector for VR above Napa online ECHVRC38 $12.64 (8.99?) "VRC38"
on a '00 miata:

Ground the case, I found it convenient to mount it near the radiator overflow bottle.
Hook the BLUE wire to switched(?) "+12v" battery voltage
Hook the GREEN wire to the Grey/Red wire on the alternator, pin 1-O on the factory ECU.

I let line 1-T hang, I'm not really sure what it is, it seems to be measuring the voltage of one coil of the generator, before rectification. Not sure what that's good for, maybe you could get engine RPM out of it, or total altenator capacity.

Anyway, hooked it all up and everything works well enough. It seems to only charge to like 13.5-13.7, I think this is due to the Mopar part only putting out 580 mV, where I got better charing feeding ~980 mV. Much more than that and you're rapidly feeding 15, as much as 18V into the system.

 

Well, it's ugly, maybe I'll clean it up later, but for now here's my pin out spreadsheet, "as is". I hope it helps someone.

It's a '00 pin out, I could probably add a bit on the alternator, as included in the last thread, but I'll have to find out what color they turn to. Basically, the grey/red on the alt is the control line, and the grey is some single coil unrectified refernece.

 

Still need to clean up the spreadsheet, but for those following the blow-by-blow, putting a 100 hz square wave on pin "2k" to the wiring harness makes the tach real a few k, giving it a 10 hz makes it read a few hundred.

At about 9v it stops working, so it's looking for 12+, as others have said here.

 

i have the FSM if it would help with the diagram

 

Thanks. I have it actually, that's how I made the spreadsheet. Boy, it's really helped to have this spreadsheet, even if it's in ugly form.

In in process of redoing my harness, it's SO much better now. Here's a hint: DO NOT USE RADIOSHACK WIRES

OMG! Last time, all the wires came out kinda.. bad. No fitting right, insulation swelled, etc. This time, I used the DIY Autotune wires (my GOD if they'd been 1' longer it would have been nice), and every single thing came out perfect, except the three or four wires where I used radioshack wires.

Anyway, going to get this second harness wired up, clean up the spreadsheet (I think into one big collum insteaf of side-by-side like in a parallel install), and post it. Soon.

 

Discussion in another thread, but since this is an OEM Stuff thread, here: