Dash tachometer will not work, tach in Tuner Studio works fine...
 

Hey everybody,

So I've been searching and searching about this and haven't come up with anything particularly useful in finding out what the problem is. A while ago my alternator died in my 1997 miata in a fantastic way, spiking everything with voltage and frying almost every fuse and bulb in its path and since everything has been replaced but my tachometer in the dash has been completely dead, despite everything else working fine.

I have since installed a MS3x built by Braineack and Tuner Studio reads the engine RPM just fine and everything else works just fine, just not the tachometer in the dash. I have taken the gauge cluster out and measured the voltage coming from the IGN signal to ground which is at about 12v and the TM to ground which reads at about 5.55v and seems to climb just a little bit when RPM is increased. This is also consistent with the reading across IG- and GND in the diagnostic box which is also at 5.55v and also increases slightly with RPM.

Anyone have any ideas on where to go from here? I'm totally stumped and don't know where else to look....

Any help would be massively appreciated

is tachout turned on in software?

It is on. I got ahold of an external tach a little earlier and just tested it on both the IGN port of the diagnostic box and the TM connection of the gauge harness and (while a little inaccurate) it did read the RPM. So I am guessing it's a problem in the gauge cluster?

I had plugged in a gauge cluster from a 91 a while back though and it didn't work. My research indicates that they should be compatible across the 90-97 years

no idea, that IGN output in the diag. box is getting it from the MS directly...

And doesn't the tach signal to the cluster come directly from IGN?

So weird that it would show a RPM reading on a crappy aftermarket tach from both the IGN port and the TM connection at the cluster but not on two different oem gauge clusters themselves

it's coming directly from the MS. the signal is split behind the dash and goes to the Diag. port.

Try a new/different igniter.... Happened to me,car ran great, MS had tach signal, but no Rpms on the cluster, new igniter fixed it.

IIRC ignitor won't fix it on a '97 which gets its tach signal from the ECU, I think it's pre-95 that get the tach signal from the ignitor.