Thanks for helping me with posting the pic. I just have to finish drlling the holes for the buttons and wiring them up so I can get back on the road.

Take it easy drilling the holes. Let the drill do the job and don't push down on it. The glass/plastic cracks really easy. Don't thank me, Thank Halfspec. I just posted/fallow his idea here.

Hey guys quick question on the fuel level guage did you do manual calibration or did you use one of preset ones the guage comes with.

On the one I used, you used the resistance reading from the OEM sender unit (FSM has this reading). The Speedhut unit, you can "calibrate" your empty/full point by telling it which one it is.

Hey very nicely done, I am planning to do the same thing this winter btw how did u hook up the tach? Using the oem pcb signal or get it from the cpu?
Khris

I got the the RPMs signal from the cluster wiring harness.

ok cool, I saw u cluster on speedhut gallery and it look awsome I did not know who it was I gonna do a search but something tell to come on the forum and that's when i saw ur original post.

im adding mine to this older thread in case someone stumbles on it looking for a solution. my car is a 78 and that is a fiberglass copy of the stock gauges with the holes cut for the speedhut gauges.

That's pretty awesome.

Attachment 757433
Attachment 757434

What size was each gauge you used from Speedhut?

4" for the tach and speedo and 2 1/16" for the others.

Thanks, that's what I have in my cart right now just wanted to verify. Hopefully I can order them soon, though I have more important items to get in the mean time.

Great work here guys. Really liking that FB retrofit too!

Just bought the Speedhut gauges last night and this is exactly what I was thinking...keeping the stock speedo hooked up and behind the gauge cluster. It's not like anyone will see it anyway. I'm going to try it this way. I'll let you guys know if it works.

Is it possible to use the non-GPS speedo if you don't have cruise control? I want to do this project soon but I need to check the legality of GPS speedos as the main speedo over here in the UK.

Cheers :)
Paul.

Whether its a GPS or non-GPS speedo has nothing to do with the cruise control, so you should be fine either way. I don't believe either of them will support cruise control so I'd have to modify the stock speedo to keep cc regardless.

It's just that the GPS speedo is easier to install.

Cheers. I wasn't sure with it being mentioned about keeping the stock speedo somewhere that it was required or not.

I just checked and GPS speedos aren't legal in the UK.

Think we really need the whole speedo... or just the guts that convert the signal?

I bet someone electronic savvy could make a signal conditioner that would eliminate the problem altogether

A buddy that has 20+ years of experience with electrical like this looked at my speedo and said I need to keep the speedo motor and odometer box on the board in order for it to work. I found a 16-track ribbon that he's going to trim down and solder to the ribbon on the back of the cluster for me so I can remote mount the speedo board behind the cluster. I was looking for a 15-track ribbon with a connector like stock so I could just extend it but I was told that would probably be impossible to find.

I'd much rather find a way to do without the board but I'm not great with electrical so I'll trust my buddy lol.

So my buddy soldered the extra length of ribbon onto the cluster ribbon for me, I wrapped the speedo circuit board in bubble wrap and slid it between the top of the cluster and the bottom side of the gauge hood and it fits there pretty well, holding itself in. However, I tried cruise control the other day and it didn't work. So I'm thinking the board needs to be grounded or something. Makes sense now but I hadn't thought of it before. I might do some testing with it, grounding it in different places to see what works, if anything. I'll post up again.

I also need to see why my tach isn't working. I'm not sure I tapped into the right wire, or maybe that wire became disconnected last time I was messing around back there and I didn't notice it, but I think either wrong wire or needing a ground or something is more likely. I think I got the yellow wire with blue stripe instead of blue wire with yellow stripe, but I haven't taken the cluster back out to check. Other than those two problems, I still need to set the fuel gauge correctly (I had chosen the 1/4 tank option on the fuel gauge because the ohms for that setting were the closest to the ohms for the stock float, but it didn't work).

the mounting screws on the back are the grounds

So I should get CC back if I ground at least one of those, huh? Or do you think I should ground all of them? lol I could run all of them together into one wire and then just ground that I guess, just to be safe.

Like I've told you in PM, electrical is part of my job but I HATE it lol.

And other than that, I have to figure out why I don't have anything reading on my tach. Not sure if I'm tapped into the wrong wire or what. Then I'll post a thread of exactly where you need to tap into wires for the Speedhut gauges, or at least the three that I have, then others can chime in with theirs too, and I'll post the link in here.

Try to ground them all together and make a common ground. Report back please.

Yeah I'll do that. Thanks!

Well, no luck. Actually it's worse with them grounded, because not only does it not work, there is a super annoying infinite beep lol.

This is what I came up with today to ground the board...
Attachment 661578

I also grounded one of the spots where there was no screw going into the board, but it said it was a ground, so I figured I wouldn't chance it. Too bad it still didn't work.

And here is the back of the board, with the extra ribbon soldered on, but I already used liquid tape and electrical tape on the joint so it would be protected. I didn't realize until now how shitty and dark this pic is lol.
Attachment 661579

And this is how the gauges came out. I wish they were a little brighter, but oh well. I still love them.
Attachment 661580
Attachment 661581

There has to be a way. Let me see if I have a chance this weekend and I will dig through schematics. Gauges came out nice.

That would be great, thanks! My buddy that soldered the board said he'd look through schematics too but he's pretty busy these days. I'm wondering if it needs to be grounded to the circuit board somehow.

I just remembered I wanted to ask, nothing from cruise control goes through the airbag ECU does it? Because I have that unplugged. Just a thought.

Did it worked before the cluster swap?

Yeah it worked before the cluster swap, but I also pulled my passenger side airbag at the same time and unplugged the airbag ECU. I also pulled the dash and rebuilt the HVAC boxes but I don't think that would have caused any problems, and I also pulled the old Viper alarm out of the car and respliced wires, which I think probably caused my stock alarm to start working again.

Well the schematics for the cluster aren't that detailed. What I would do, is try one ground at a time.

Is the reason for modifying the stock cluster and mounting the gauges that way for aesthetics only? To have all of the gauges flush behind the OEM glass, instead of just say simply placing the new gauges in the holes in the cluster surround?

I mounted them that way so I can make them look OEM and still have the warning and blinkers lights work.

You're talking about the grounds on the speedo board, try each of them one at a time? Or you're talking about trying a ground at a time troubleshooting in general?

Yep, that's why I did it this way too. I did mine a little different though. I cut each hole out, then put the gauges through and fiberglassed a strip behind each one to hold it in place. To make sure they were centered I measured and drilled a little hole on each side of each gauge (on the clear plastic front) so the gauge itself could snap into it using the little tabs on each side that hold the Speedhut clear cover in place. I have pics. I'll post them up in my own thread and link them here. But I'm trying to figure out all this wiring first so I can put that info in there too.

I'm also having trouble setting the fuel level on the gauge. First I tried one of their ohm settings but they were close enough. I drained the tank and added a few gallons back in and set it to empty. Then I drove to the gas station and filled it up and set that to full. But now the level isn't dropping and I've been driving the car all weekend. I'm getting really frustrated with this thing.

Any updates? I don't want to lose cruise control doing this.

I haven't messed with cruise control any more yet, but I too would like to know if someone else found a solution.

Anyone ever try this mounting method but use revolution black bezel?

Any one have a wiring diagram for this for some reason my rev counter and shift light dont go

Disregard, for some reason I was thinking the stock cluster schematics. Speedhut might help you out but I'm sure it would void your warranty. They're usually pretty good about taking stuff back and fixing it.

Good news, guys! Another friend and FD owner on this forum (I don't remember his screenname right now) drew up a schematic for a circuit board that should work to get cruise control back, and another friend and FC owner (I'm not sure if he's on this forum but I think so) is finishing up electrical engineering and he's going to make the board and I'm going to try it out. It'll still be a few months because he needs to graduate first and I need to get back to the US haha, but I'll let you guys know how it goes. And I'll talk to them and see if they want to make a few more of these boards for people that want them. I'm not sure what they'll charge for it, that's up to them. FINGERS CROSSED!

Has anyone tried the Dakota Digital converter for conditioning the speed sensor output to the cruise module input?

From my reading it appears that the sgi-5 will downconvert by half an input signal and convert sine to square:
http://www.dakotadigital.com/pdf/sgi-5c.pdf

That seems like it produce a stable enough signal to the cc module to allow it to control speed? I don't think there would be a need for recalibration of the output, according to some reading I have done the range of the cc module is wide, so as long as the signal is within that range and stable my guess is that it might work...

This is basically the reverse use of the sgi-5 from the ls guys, who use it to double the ac sine from their vss to the Mazda speedo and recalibrate.

I'm interested in this as well as I'm working on a Dakota replacement (USB + computer programmed (no stupid dip switches) for a fraction of the cost) and it could also be used for this application if the Dakota can do it. I've read the same thing that the stock speedo takes the sine signal from the fd's speed signal and converts it to a pulse train, but do the actual specs define that, that frequency is halfed before sending it to the cc module or has that just been observed? Any references?

Lane

Hi Lane, thanks for chiming in! I have read a bit of your postings and about some of your experiences too, glad to see you here....

I started a thread in the 3rd gen section, and did a bit of reading over the weekend and collected some relevant data:
https://www.rx7club.com/3rd-generati...ignal-1076007/

I haven't seen where anyone has measured the output of either the factory or the Dakota box. Based on piecing together the stories from the wiring diagram(voltages) and the service highlights(showing pulsed 1/2 output to ecu/cc), it would appear that the factory unit halves the ppm signal into a 2-2.5v sq pulse, so 8200ppm to 4100ppm.

I actually found a very good description of the internal circuit process somewhere, I will see if I can dig that back up tomorrow. Most of this is above my head electronically, but I'd love to see your arduino solution working. That could be great for all of these use cases.

I'm willing to guinea pig the Dakota on my car when it's back running in a couple of weeks to see if it works. I have a new cluster coming in 5 weeks or so and don't want to lose my cruise.

Hey, guy just brought the speedhut gauges and im just wondering which wire on the ignition module i need tot splice in order to make the Tach working properly? Search and cant seem to find the answer. I look at the wiring diagram and i think it Light Green wire. Please correct me if im wrong. Want to make sure before i start cutting into wire and splicing them.


Thanks

I tapped into my pfc wire 2B to the speedhut yellow wire, right out of my pfc. I'm not sure which wire in the factory connectors was carrying this signal(and didn't find it obvious in the fsm/diagram) and it was easy enough for me that way.

Hey guys due to some bad wiring i had to remove my factory harness. which is okay because im full stand alone.

I need to find a good wiring diagram to figure out which wires do what off the back of the factory gauges. I would love to swap them but next year. if anyone has anything that would be awesome thanks!

Are you looking to see which wires to tap into for the different gauges? I'll have to see if I still have some diagrams showing which ones to tap into.

Has anyone else done this?

It sucks that the picture links throughout this thread are broken. I know Half-Spec did a pretty in depth write up on his setup, but it involved quite a bit more than the average gauge install would be.