I want to put an NB cluster in my NA so that I can maintain a factory looking cluster with an odometer and not have to use a cable to digital converter box. I've spent a good bit of time looking around to try and find information regarding the swap but nothing very descriptive. From what I've seen it's been done numerous times.

 

I did it. The biggest problem, obviously, is the wiring. The NB has 3 connectors, the NA has two, so there is a lot of splicing going on. Be sure to get the NB pigtails. I took it a step further and transferred the NA oil pressure internals over, the NB gauge is set up to be an idiot light so it doesn't really read realistically. The temp gauge isn't real linear, either, but it seems to be acceptable. You need to add a 12v constant hot to maintain the tripmeter readings.

The alignment studs are slightly off, a little work with a rat-tail file or a dremel is necessary there, but the screws are in the right place.

Mike

 

I'm also using an NB cluster in my Ls1 NA did you adjust the speedo in the GM ECU or use a converter box

 

I've only collected the cluster and wiring, I haven't installed it yet. There are others here that have done it, hopefully one will chime in.

 

I'm sorry I missed this in April Steve. I was frantically getting ready for the Mitty and I spaced a lot of things that month! I think the reason you are not finding much on it is because there is really nothing to it. But this will be the thread that spells it out!

The NB head itself goes in the NA dash with no mods at all. Same size, same shape and everything. I'm sure you know the wiring is different and there is 3 plugs on the NB but only 2 on the NA. So when you buy a head be sure you ask for the plugs with a little wire too.

To wire it up just take the wiring diagram for the NA and NB dash and one wire at a time hook the NA harness wire to the right place in the NB plug. Power to power, ground to ground, tach to tach, etc. There are a few on each plug that are not used. Wiring diagrams can be found here. Miata Forumz - Mazda Miata Chat Forums

Don't count on this being right for your years but it will give you an idea of what you are doing.


Now there is one wire you need to add here that is often missed. Truth to be told I missed it and have been running it this way for the last 15000 miles but in a good build you would want to add this wire. The NA harness doesn't have an always hot (+12V) connection and the trip mileage memory needs it to remember from trip to trip. In the chart above you see it as the blue/red wire and there is no mate to it in the other column. So if you don't add it the trip mileage will work until you shut the car off then it will reset to 0 every time.

For the speedo you need a converter because the GM computer sends a different pluse rate than the Mazda one. But it's no biggie at all. This is the Dakota Digital unit you need.
Universal Speedometer Signal Interface

So back to the NB wiring you add 2 wires from the Dakota box that the NA harness dosn't have. I have seen the VSS signal to the Dakota box done 2 different ways. 1 is splice into the VSS signal straight from the trans and the other is to use the VSS output from the computer. I did the former but it works either way.

This is how the dip switches go on the Dakota box using the direct VSS signal.


The 2 wires that go to the NB speedo are out and sensor ground but I just ran the sensor and normal ground go to the same ground. It is not really clear in the wiring Mazda wiring diagram which is signal and which is ground on the head but it dosn't toast anything to get them backwards. It dosn't work backwards though.

If you are doing an LS1 the tach needs no mods just run the wire to the GM computer. It's a white wire and off the top of my head I think it's red plug #10 in my 02 Camaro harness. Gas gauge needs no mods and I did not use my oil or temp gauge because they are not gauges. I covered the temp gauge with an UltraGauge and I have no idea why my oil pressure gauge appears to work when there is no sender wire going to it.


LOL yes the gas gauge works and I usually don't run it that low!

I think covers it but if not give me a boot and I'll wake up to help!

 

Thank you Jim for that info I've been working on putting that chart together for a few days now and looks like I was on the right track. I'm not sure if I met you at the Mitti or not what car was yours?

 

I don't think we talked but I know your car very well. Not sure where I dug them up but I have a whole folder full of photos of it. I looked long and hard at copper cars for months looking for the ideal copper to do just what you did. Which I believe you totally nailed! Ended up just going a semi gloss black and decided to run for a summer with no stripes. The hood is so busy I'm not sure I want to stripe it now. But sooner or later something will have to change...

Mine was the semigloss black one with bumpy fenders...


Or in her Sunday best with spats and flaps on...

 

You said the tach requires no mods? According to the flying miata wiring guide they say you need a resistor inline with the tach signal. 2.2k iirc. What do you think about that?

 

Jim That's the one I had in mind. Thanks it took a week mixing paint to come up with that color and we didn't write it down.

 

Yeah I remember reading that too but you don't need it. When I first wired mine up I watched the tach with a scanner off the OBD port and it was spot on. I forget what the resistor is for but maybe for some years or the erod computers FM uses it's needed. I can say for sure that an 02 Camaro and 96 Miata work perfect with out it but no clue on other years.

 

hmm, well mine is already wired in. oh well, would be simple enough to remove it if need be.

 

Ok I've got the cluster in and everything works but the tach. I'm tied in to #10 on the PCM (mine is brown) and green w/orange. I looked at the link above and it opens a blank page, any other ideas?? The cluster I have is from an 05 Miata speed.

 

So, what is the benefit to the NB cluster to make the swap into an NA?

Also, I'm curious about the cruise control function. I have to assume that the NA cable driven speedometer must have a signal generator (VSS?) in the cluster to create a cruise control input function of some kind.

 

What links are not working for you Scott? I tried them both and they open right up where they are suppose to go.

My only thought is perhaps the GTO computer output signal is different than the F body and I bet Pat would know if that's the case... https://www.v8miata.net/general-moto...ina-794/page5/

 

Because the NB uses a digital speedo rather than a mechanical one so for GM builds it's a much easier interface. Sorry I have no clue how the cruise works in either as mine didn't have it and the aftermarket unit I put in just holds the RPMs constant.

 

Yeah, it's a high-tech reed switch pulsed by a magnet that's attached to the driven part of the speedo internals.

Mike

 

The link opened after I made the post. I'm going over all the schematics and Will double check all my connections Saturday. I will post what I find.

 

I'm absolutely no help here... All my aftermarket gauges (except for fuel) read thru the OBD II port. I took the lazy way out of this one!

 

Are you using the pull up resistor on the tack signal wire coming out of the ECU? If not then you will need to add a pull up resister than every thing should work with the setup you have been provided. I use a LS 2 gen-4 Corvette engine with E38 ecu and it requires one in order to function.

 

I thought he said he put that resistor in but now that I read back I see not. So that's the difference in the Fbody to the GTO!

 

I am not getting any signal with or without the pull-up resistor. I'm just going to order auto meters tach signal generator and tie into the coils.

 

Well I had the info that I needed all along in the form of FM build manual that I did not completely read! The correct way to connect the tack using a 2200 ohm resistor is to use it as a jumper between the tack signal wire and the black w/yellow 12v ign wire. LOL I was making it harder than what it was, a ten minute fix!!

 

Here to add info/correct the chart up there.

The feature labeled"illumination" and the grey/red(NB wiring color) needs to be a ground and if you take the red from the NA harness it's a 12v so the illumination won't work.