Glow Shift 3 Cyl Tach in a Metro
 

Hey all! :D
(I LOVE this place!)

I just recieved my GlowShift Tach.

The wiring setup is a little different then what I kinda expected,
and would like some help with setting it up.

Theres a 4 wire plug labled as such:
Black: Engine ground
Red: Switched ignition source(+)
Orange: 12v Dimmer wire switch(+)
Green: Tachometer Signal

My question is with the green wire.
Where do I hook this one up to?

The instructions are:
The green wire get connected to your vehical's tachometer source wire. On some applications it may be necessary to use a tachometer adaptor.

What is the Tachometer Source Wire?
And do I require an adaptor for the GEO?

Hook it to one of the coil wires. I can't remember what one is correct but you can always touch it to one of them and see if it is working. If not then try the other one. It won't hurt the tach being connected to the wrong side of the coil. The other option is connecting it to the coil wire coming off the ECM but that is a real pain to get to so I say hook it to the coil and save a lot of hassle.

AFIAK, you want the ground side of the coil, possibly the black/white wire.

Thanks Guys!
I'll be installing the tach tonight....

K, splicing in a moment...
I have a Black/White wire, and a Brown/white wire...

Hope nothing goes BOOM!

If you give me the model year and if it's MPFI or TBI, I can send you a schematic.

The car is a 1994 GEO Metro, TBI
The engine is an earlier year... (thinking a 92/93 - but not sure)

Thanks!

Well, I spliced into the black/white wire, and got nothing...
Then the brown/white... started to read correctly...

But one weird thing is happening now... the idle seems high, and is oscillating between 1000 and 1800 rpms... I hear a little 'click' and then the rpms jump in speed...

Is that due to the altinator?

Is the engine running fast, or is it the tach that is displaying the incorrect rpm?

With the engine cycling the way it is now, its running fast...

With the timing light(before the tach install) Idle was timed at 850rpm.

Not sure what its doing... but I'll pull the batt and reset everything... see what happens.