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Old 01-23-2013, 08:37 PM   #1
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Default Using MS3 Harness as a Template?

Hullo everybody!
I'm going to rewire my car. Far too many piggyback, helper boxes, signal interceptors, etc have been through it, and much of it was done with an eye towards testing, not reliability.

Of course, I've yet to decide on an ECU. Rather, I have decided to run several. So I want to make a harness for the car which brings all signals of interest to a common, cheap, durable, well-defined connector - something I can easily, cheaply create boomslangs for to take me to wherever I need to be.


One of the computers I'm looking at uses these pretty sweet Molex connectors.. But there's no mate for it! It's to a board mount only.

Anyway, thinking about cost of replacement, ease of working with, the DB37's of Megasquirt fame seem reasonable.

The question is - what's the point of the original connector on a modern MS3X? Would I be using it for anything beyond ground and +12V? I guess I'd like to get as much "signal" on the MS3X connector as I can?

Basically, what would be the wiring diagram for an MS3X, and, how could I take advantage of as many other signals as possible in a way which won't preclude my someday possibly plugging an MS3 into it (i.e. ETG signals, VSS signals, Oil Pressure, as well as the normal temp sensors, cam/crank, full sequential (possibly two banks of injectors) etc etc.....)


Perhaps I should state my question in the form of a question, but there you have it. :-)
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Old 01-23-2013, 09:17 PM   #2
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Quote:
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The question is - what's the point of the original connector on a modern MS3X?
Off the top of my head, the lower (classic) connector on an MS3 equipped with the MS3X would convey:

Power
Logic & sensor GND
Crank sensor
Coolant sensor
Air temp sensor
O2 sensor
TPS
Vref



As for an ideal universal connector, have you considered the Molex Mini-Fit Jr? This is the same connector that's used on the ATX power supply in your PC. They're available in both male and female versions for wire-end termination, in a variety of sizes from 2 to 24 circuits per connector. We use these are PR&E for all of our DC power interconnects. They have very nice contacts, and interlock securely but are easy to separate by hand.

I would think that for an average Miata, two of those (say, one 24 pin and one 22 pin) should accommodate everything with room to spare. Frankly, I hate the D-sub connector for automotive purposes.

Molex - Mini-Fit Jr.
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Old 01-24-2013, 08:20 PM   #3
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Why are you such a hater on DB style connectors?

Quote:
Power
Logic & sensor GND
Crank sensor
Coolant sensor
Air temp sensor
O2 sensor
TPS
Vref
Thanks for the list - that makes me even less likely to really want to use a second DB37... I just don't like the idea of two plugs, right next to each other, which mate but are cause horrible, irreparable damage if they get plugged into each other. It's why I always bring my own sleeping bag when camping with a bunch of dudes.

Quote:
Mini-Fit Jr.™ single- and dual-row connectors handle current 13.0A and are ideal for wire-to-wire and wire-to-board application requiring design flexibility


Mini-Fit Jr.™ is ideal for higher-current / higher-density applications which require design flexibility for wire- to-wire and wire-to-board configurations. Mini-Fit connectors are ideal for power applications up to 9.0A per circuit.
I can't imagine they mean 13A/connector but up to 9 for any individual circuit... I guess a few people's houses burned down and they cut back their recommendation?

Either way, not a bad call at all. Maybe I will do that way. The DIYAutotune harnesses DO have the more-or-less individually labeled wires.... Do you have a good source for reasonably priced numbered oil-and-temperature resistant wire? I've had little luck tracking that down... But if I could, yeah, making my own would be the way to fly.
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Old 01-24-2013, 09:40 PM   #4
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Quote:
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Why are you such a hater on DB style connectors?
Strain-relief is a pain in the *** for large bundles.
Wires larger than 22ga don't really fit properly on the pins.
Those screws are a serious pain in the *** to install and remove when the ECU is mounted up under the dash.
And they frequently break.
Or cross-thread, because D-sub connectors from different manufacturers freely interchange metric and SAE screws.
And because not racecar.




Quote:
I can't imagine they mean 13A/connector but up to 9 for any individual circuit... I guess a few people's houses burned down and they cut back their recommendation?
Can't say for certain. At work, some of our stuff draws up to 10A at 48v, and we've never had a problem with 'em.

But it's definitely more than 13A per connector.

Think about an ATX power supply in a PC. Some of those bitches can legitimately deliver 40+ amps on the 5v and 3.3v rails.
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Old 01-25-2013, 03:24 PM   #5
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How come the more good answers there are, the further I get from a decision?

I guess no magic source for wire bundles, eh? I've had friends just buy a spook of aircraft wire. Can't argue with the quality, and the cost isn't crazy... But then you have 100 identical white wires... hard to pick the right one at times...
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Old 01-25-2013, 03:28 PM   #6
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2x on the atx power supply cable.

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Using MS3 Harness as a Template?-1295686139942eq2.jpg  
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Old 01-25-2013, 03:31 PM   #7
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Wholesale F04215 20 Pin Male to 24 Pin Female ATX Power supply Adapter Conveter cable wire connector For PC, Free shipping, $2.63-2.69/Piece | DHgate

Get an extension for psu and you should have both, a male and female connector.

Let me find u a better more reputable link.

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Old 01-25-2013, 03:35 PM   #8
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Newegg.com - Rosewill Model RCW-304 8" EATX power supply 24P Male to ATX 20P Female motherboard Cable

This one is made for offset power supplys. It will work however only 20 pins. 4 pins on the male are staying out.
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Old 01-25-2013, 03:43 PM   #9
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Grr i keep finding better ones, here you go this is a 24 to 24 pin cable. This is the one you want.

Newegg.com - StarTech Model ATX24POWEXT 8" Power Extension Cable for 24 pin ATX 2.01 Motherboards

I dont mean to crap your thread just keep finding better ones.
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Old 01-25-2013, 04:39 PM   #10
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There's no need to keep digging up ATX extension cables. Abe is a big boy, and he can handle purchasing the shells and terminals separately and terminating them himself.
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Old 01-25-2013, 04:45 PM   #11
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Well i was specifically looking for the 24 to 24 cable but kept finding the 20 to 24 cable.
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Old 01-25-2013, 05:18 PM   #12
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No need. Molex Mini-Fit Jr. connectors are cheap to buy and easy to terminate.

And quite handy for building ECUs out of. This is my previous ECU:





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Old 01-26-2013, 03:00 PM   #13
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No worries about thread shitting - most of them start that way if I write them.

Joe's got a point though - not that I don't love someone to source them for me, because I do - but I DO want to crimp it myself.... The whole point of this exercise is to remove unneeded solder joints, crimps, and splices in my harness.

Joe joe joe.... What IS that? Link/pics/info? Please tell me "PIC" is not a pun.....
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Old 01-26-2013, 03:10 PM   #14
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Joe joe joe.... What IS that? Link/pics/info? Please tell me "PIC" is not a pun.....
It's an ECU that I built early last year when I was bored and had some time to kill. I call it the Hellasquirt.

It's an homage to all of the various Megasquirts out there which are built on the "classic" rev 2.2 / 3.0 / 3.57 PCAs, and subsequently covered with hacks and jumper wire in order to make them function on a modern car. I figure that if some jumper wire is good, building the entire ECU out of jumper wire must be better, right?



I realize that to some folks that will look like an incomprehensible rats-nest, but it's really not very many individual circuits at all. It's amazing how little it actually takes to run an engine. (And no, I'm not proud of the solder blobs. Sometimes it's just the easy way to get the job done.)
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Old 01-28-2013, 01:18 AM   #15
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Huh. That was totally my call when I saw it... I was on the fence if you'd be homeaged out to the MSI or try to pit together a II or III.

It's a shame there's no way to make nice, printed MSI and MSII's with one decent board. I guess it'd be a microsquirt? Anyway. The future is here. Deal with it.
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Old 01-28-2013, 04:20 AM   #16
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Another nice thing about the ATX connectors (I guess most crimp pin connectors that don't have weather seals...) that I like is that you can stick a probe in them through the back while everything is still connected, contacting the back of the pin, and it will typically fit snug between the wire and housing so you don't have to hold it in there with your hands. That way you can set the probe and have both hands free to fiddle with whatever pieces/software you are actually trying to adjust until you get your desired/undesired outcome during testing. DB connectors do not afford you this bonus functionality.
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Old 01-28-2013, 09:23 AM   #17
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My bazooka tube uses ATX connectors.
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Old 01-28-2013, 02:01 PM   #18
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Quote:
Originally Posted by AbeFM View Post
It's a shame there's no way to make nice, printed MSI and MSII's with one decent board. I guess it'd be a microsquirt? Anyway. The future is here. Deal with it.
Well, MS1 is pretty much dead as far as I'm concerned. I doubt I'll ever do another one.

Something like that could easily be done on a PCB for the MS2. That was actually the original direction I'd been planning to go in before DIY whispered into my ear about the MS3Pro. While the price may be a tad high for some, it's still one of the least expensive (possible the single least expensive) of the "big boy" ECUs. And I'm not sure you're going to be able to get the price point much further down with something like that.

If people were seriously interested, it wouldn't be hard to do a one-board solution for the MS2. Might even be possible to do it as a through-hole board if you want to let folks assemble it themselves to really keep the price down. I just hate the idea of continuing to perpetuate old CPUs in new products...
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Old 01-28-2013, 02:52 PM   #19
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Quote:
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I just hate the idea of continuing to perpetuate old CPUs in new products...
+1

Quote:
Originally Posted by Joe Perez View Post
Might even be possible to do it as a through-hole board if you want to let folks assemble it
themselves to really keep the price down.
+2

I don't think it would have to be very big, nor would it cost much. I'd say you could do one for the MS3, but I could also see how people who've invested in that would take certain offense.

It just seems there's not a lot of choices for people who want well-made, well-conceived ECUS... How do I put this? The Miata of ECU's. Simple, you can adjust everything that matters... and it's cheap and works well.


I think thee connectors are the way to go. My biggest hang up right now is getting numbered wires. Or stripes. Whatever. I guess there's a few places that do it, I don't know how hard it'd be to buy either 40 short rolls, or one short roll with 40 wires.
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Old 01-28-2013, 02:54 PM   #20
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i buy all my wire from DIY, all color coded and labeled to match the i/os from the MS

just saying.







c wut i did thar?
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