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Dash Tach Wire for a 1978 280z


qadir03

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The stock tach counts the breaks from the negative terminal of the stock coil. A wire runs from the negative terminal, through a resistor and to the tach.

 

Probably not what you were looking for but might get you started. EDIS will most likely have a different output or outputs for you to use.

Edited by NewZed
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Ok, search all over and the wire colors behind my tach doesn't match any of the schematics that I have. Here are the wires:

 

871fbf90.jpg

 

d077bd96.jpg

 

Gonna hook directly up to the black/red wire next.

 

I've also hooked it up directly to the #2 pin off the EDIS6 module, according to this: http://forums.hybridz.org/index.php/topic/72457-edis-and-tach-not-working/page__p__688402__hl__tach__fromsearch__1#entry688402

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Don't forget that there is a resistor in line between the coil neg. (-) and the tach in the stock configuration. Probably to limit current through the coil, I would guess.

 

If you still have the wires in the engine bay you could connect there or find the resistor up by the old ignition unit in the passenger footwell.

 

I would be interested in how accurate the stock tach is compared to the MS RPM reading in the MS software (which I would assume to be accurate since it is essentially all digital). Just curious, if you get a chance to compare (or anyone else that knows).

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There is (or was) a one-wire connector right above the factory ECU. It connected to pin 1 of the ECU and this is where the ECU got it's RPM information from. I have used this same connector to drive the tach with aftermarket ECU's.

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  • 2 weeks later...

Ok, used the following diagram and connected to the red/black wire behind the 280z tach and works like a charm.

 

EDIS_tach.jpg

 

Hey, could you take a picture of your modification there please? I'm wiring up a stock '76 tach and I keep hearing about this diode mod. I have a stock ford EDIS6 coil pack.

 

Where are you pulling the V- from? Are pins 1/2/3 at the coil plug and the respective pins 10/11/12 at the module plug the negatives?

 

Is it like this?

280zEDIStachmod.png

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Hey, could you take a picture of your modification there please? I'm wiring up a stock '76 tach and I keep hearing about this diode mod. I have a stock ford EDIS6 coil pack.

 

Where are you pulling the V- from? Are pins 1/2/3 at the coil plug and the respective pins 10/11/12 at the module plug the negatives?

 

Is it like this?

280zEDIStachmod.png

 

Hi Hardwyre,

 

We actually ended up using a different setup and used an MSD 8920 tach adapter. Click here for PDF diagram.

 

But your diagram above should work. The 1/2/3 pins at the coil plug are the coil (-).

 

I hope that helps!

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Hi Hardwyre,

 

We actually ended up using a different setup and used an MSD 8920 tach adapter. Click here for PDF diagram.

 

But your diagram above should work. The 1/2/3 pins at the coil plug are the coil (-).

 

I hope that helps!

 

Having the -/+ question does help, thank you. I currently have a single coil 6AL + Blaster Coil 2 + 8910 Tach Adapter, but I'm really excited about putting the Z in a distributorless dress while cleaning out some of the engine bay components. Figure if I can wire straight into the tach, I can get rid of a few wires and boxes.

 

Anyone know if there is a thread outlining all of the stuff you can remove after an EDIS + Megasquirt upgrade? I'm sort of figuring most of the stuff on the left side of the bay can go (junction block, drop resistors, pretty much anything that connected to the ECU harness). Also still need to track down which wires are good for switched 12+ which stays on while cranking.

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