Standard tacho not working w/electronic ignition

[NSharpley]

So ... some history.

My GT had a crappy non-standard tacho in it thanks to the previous owner.

I ditched that and obtained a lovely standard tacho.... the problem is it just doesnt work.

I can confirm the tacho did work in its previous car.

The only connection is the standard harness so I'm not surprised it doesnt work because there's no connection from the electronic ignition to provide rpm (I am reasonably sure thats how it works).

I have a wire from the coil that went to the old non-stanard tacho but Im not sure how to integrate that connection into the standard tacho.

Any advice?

[alanm]

Frankly Mr sharpley... Isn't there a song with those lyrics?

Anyway, I had some issues with a tacho that I Captured in a thread.
There might be something in there that sheds light, the problem drove me nuts until I found a solution.

Search this forum for
Alfa 75 after market tacho

Cheers, Al.

[carlo rossi]

the newer tach uses a harness the older just wires i believe it shoulkd conect like any other
after market tacho unless it has a hrness send photo of it

[GTVeloce]

Working from memory here but I think the tacho didn't use the harness. It was a floating single wire (white) that goes from the distributer to the tacho. Have a look and see if you can see a single white wire somewhere in the region that isn't connected to anything.

[John A Pucak]

I thought the GTs had a mechanical cable for the tacho that ran off the front of the engine somewhere.

[NSharpley]

I thought the GTs had a mechanical cable for the tacho that ran off the front of the engine somewhere.

Indeed it does ... but this is a 2ltr out of a 78 model.

Plus, electronic ignition so doesnt use the cable drive.

[carlo rossi]

so it should have a harness connection then
for the signal lights etc

[NSharpley]

so it should have a harness connection then
for the signal lights etc

It does, yes ... and tey all work fine ... I just need to get the wire from the coil connected somewhere so the needle actually works.

No idea about that one.

[Citroënbender]

Have you tried either dummying the tacho input or using the signal into a different tacho or even a scope?

[NSharpley]

Have you tried either dummying the tacho input or using the signal into a different tacho or even a scope?

Dummying the input?

I did have a tacho in there, and it was working fine ... but it was non-standard and looked crap.

I can put it back in and it works (tempted to do this and shelve the standard tacho for another time).

[NSharpley]

Is the electronic ignition from a later Alfetta 2.0L or is it some other type, Regardless of whether the ignition is points or CDI the tacho is triggered by the ignition coil via the negative terminal it is usually a white wire. You will need to replicate the wiring and connector from a 2.0 GTV. Does you new tacho have the same 8 pin connector as in the photo

Hi ... its an after-market electronic ignition from Vin Sharp at PACE Engineering.

It does have the 8 pin connector ... I want to say there are some missing wires though.  Ill take a pic tongiht.

The speedo and tacho have been swapped so there are some changes to the layout.

[NSharpley]

Or you could try and bypass the wiring loom connector and run a direct connection from the NEG coil to the tacho and an earth wire from the tacho to any grounded point as a simple test.

I can do that but where on the tacho does the wire from negative on the coil connect?

[bonno]

Find attached photos of the instrument cluster in question. This was taken couple of years back when I developed a power point presentation for the refurbished GTV split dash.