speedo and tach died last night on my FD
 

So after repairing the brakes and adjusting my idle so it is not bouncing all over the place. I took the FD for a long drive as a DD in the heat of the afternoon in Tampa, FL.

Towards the end of the night I made a pit stop at Sweet Bay and then when I got back in the car to leave both my Tach and speedo had died. Everything else seemed to work, but just no tach or speedo.

I know I have read in a couple of post that this has to do with the ground on the car. Is there an easy fix to get this working?

The tach and the speedo on the car had been working perfect.

Happened to me last year, bad speedo. Speedo powers the tach and I think the odometer. There were only a handful of new left if I recall correctly. While it could be a grounding issue my money is that it failed just like mine. Pull it out and check for cold solder joints if you don't find anything obvious I would start sourcing a new speedo or cluster.

Despite what a few sites claim the FD cluster only has a few serviceable parts the rest are replacement. The service part aren't typically what fail. I sent mine off repair to save the odometer reading, they were unable to repair it.

Oh damn that sucks. So what would I do, find the ground for the speedo and see if I can splice the ground and if that works then it is obviously a ground issue. If it doesnt then i am looking at a bad speedo gauge. I hope it is a ground issue because I have a power FC and my A/C doesnt work because of a bad switch or bad ground.

Also my tack works on the power FC controller, but the MPH or KMH does not. Does that mean anything?

Welcome to my world. Mine don't work either. The cause of mine?

http://img813.imageshack.us/img813/3...0408173033.jpg

Been calling around to see about getting it fixed. Some shop want a working one so they can get the values of the diodes, others are shooting from the hip and quoting me a very high price and others would not even touch it.

My solution? Just going to replace all of them with these. Kill 2 birds one stone since I want to go with the Spirit R cluster. This way I can have them the way I want them with more accurate gauges without the cluttered of having gauges all over the place.

http://www.speedhut.com/gauge_produc...uto=revolution

I thought about doing the spirit r cluster. I just wish they made the speedo in mph.

The power FC get those reading from other sources it's consistent with the problem. As for your AC I assume that you have checked that it has refrigerant, if out or too low it disables itself.

I seem to recall that there is an issue with the AC and the PFC, I think that one is well documented. I replaced all that too last year, must have got the parts from the same bin... Early 94 touring here.

If it it isn't a groud with the AC I would try and build a custom AC setup from a more populare vehicle. FD AC parts are extremely expensive and IMO only marginal performers at best on R134. While my AC works for about $2500 it's nearly useless at idle and barely cools at speed. Every part in the engine compartment was replaced. I was one of those deals were it started with just the compresor and ended with replace that too while you're in there it's another $200.

so no one has actually found the values of the cluster diodes? Could this be the same diode used to correct the missing millage counter? Mine never worked.

My issue is that i dont want anything after market as far as gauges. I would like to keep the stock gauges on my car.

I know of someone locally that will check that out for you, well in St. Pete anyway. PM me if you want the info.

The secret decoder, I can't tell from the pic. Looks like black black gold on my display...
http://www.ehow.com/facts_7256252_do..._s-value_.html

Actually you can have it read MPH. Which the faces from the US cluster with the Spirit R cluster. Not only it will read in MPH but you will have your actual mileage too.

I know but with the prices they go for, you would hope they would mock some up, for people like me who want to keep it MPH. Like do up 2 clusters with the 93-95 speedo in it, already assembled etc.

Idk, i think 800+ bucks, plus you still have to do the switch yourself is a bit much.

But i guess cant have everything. Those clusters are amazing though.

I see what you are saying. Reason why I'm replacing all mines with aftermarket units for about the same price.

Damn i need to know the value and the voltage these diodes are rated for. I found a shop that sells them locally. If anyone can help me with this. I am willing to help other members out and solder their speedos for them :)

I found a local shop that sold the diodes. I also replaced the cap for the miles counter. My Tach is working again, but my speedo and miles counter still does not.

I am pretty confused

Also do the 4 solder points that connect the speedo gauge itself to the back where all the electronics are. How important are these?

check this thread out

https://www.rx7club.com/showthread.p...ht=cluster+fix

BTW those are zener diodes. If you replaced the same one as the one I have that are burnt out, what values are they?

I have see that thread and I am just about to replace every single component on that damn board.

See my biggest question is that once you remove the bolts holding the speedo in place is the speedo supposed to move back and forth out of the board? Mine does it seems that the pins holding the Speedo gauge and needle to the board allows for movement but you cannot remove it without removing the solder.

Speedo/tach
 

My speedo went out, I replaced it with a new one. The car was completely rebuilt from the groundup, new motor etc. So I was fine with letting it say 0 miles. But I'm looking into finding a schematic for these things, don't know if mazda would be willing to supply it but I will investigate that route. Then I can fix my old one as well. If anyone else has some contacts let's see if we can get the proper documentation. This will only become a bigger issue in the future. Even if you have a new gauge determining the appropriate components is not always easy.

you speedo is also supposed to be solder to the circuit board on the four points.

I know, but those 4 points move on my gauge. If you try to move the gauge assembly without undoing the solder mine moves in and out. I dont know if this is normal.

Mine is solid. Did you change the diodes? What value did you get?

I have to wait till i get home to check for you. The guy at the store said that there were only 2 part numbers for those diodes and that they were both same in specs.

I wonder if I can open the gauge motor and solder those connectors again. I am not sure how they came loose.

so i replaced every cap on the board and i still have a tach but no speedo. I am not sure what else to do. Could this be a ground problem?

I lied. I have a tach and speedo working. The only thing currently down is my ODO.

So last night my ODO came back up. When i turned the car off and on again it came back up. What could this be?