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ETB 80mm tacho & Megasquirt
scudderfish - 2/7/10 at 01:34 PM

I'm trying to wire up my tacho with no joy. Going by this doc http://www.extraefi.co.uk/Drawings/PDF_Files/tacho_Wiring.pdf there seems to be a wide range of 'suck it and see' fiddling with resistors. Has anyone got this working, and if so how? What values did you use? I believe I have a signal feed from my MS as I also have my old coil based tacho. I plugged a relay in as documented and it buzzes away like a mad thing. Needle didn't twitch though

Regards,
Dave

phoenix70 - 2/7/10 at 02:03 PM

I used this diagram to get mine working.

Linky

if you tacho was normal coil driven this will work.

BenTyreman - 2/7/10 at 02:04 PM

My VDO electronic tacho works using this circuit.



Can't remember the exact values of resistor.

Also had it working using this circuit.



Link to manual

02GF74 - 2/7/10 at 02:14 PM

quote:
Originally posted by scudderfish
I plugged a relay in as documented and it buzzes away like a mad thing. Needle didn't twitch though



if you wired the coil (realy) as shown in the diagram to the EFI signal, this shows that you have a signal. As you rev the engin the buzzing speed should increase.

Do you have the ground (0 V) connected to the rev counter?

If you take a big bolt, connect to 12 V and then run a single wire up and down the the thread connected to the tacho (causes rapid pulses) you should see the needle move.

If not, then it is broke.

errr, hang on, just read the instrucitons - it is dealing with wiring 2 differnt types of tacho to the board.

what type do you have? is it low signal or high whcih takes signal from ignition coil.

[Edited on 2/7/10 by 02GF74]

Mal - 2/7/10 at 02:47 PM

If non of the above suggestions work send an email to Phil at Extra EFI.

omega0684 - 2/7/10 at 04:47 PM

if you have an electronic input on the rev counter just connect it to pin 2 on the edis. That the rev counter output.

scudderfish - 3/7/10 at 12:03 PM

quote:
Originally posted by omega0684
if you have an electronic input on the rev counter just connect it to pin 2 on the edis. That the rev counter output.


Result! Ages ago I asked Phil what it was for and he said ignore it. Plugged it straight into my non-coil tacho with no resistors and it worked fine. Thanks for all the suggestions guys