qadir03 Posted December 17, 2010 Share Posted December 17, 2010 Hi guys, just installed Megasquirt with EDIS and want to use the tach output signal to drive the dash tach. Trying to locate the tach signal wire under the dash, anyone know where this is? Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 17, 2010 Share Posted December 17, 2010 (edited) 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 December 17, 2010 by NewZed Quote Link to comment Share on other sites More sharing options...
qadir03 Posted December 23, 2010 Author Share Posted December 23, 2010 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: 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 Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 23, 2010 Share Posted December 23, 2010 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). Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted December 23, 2010 Administrators Share Posted December 23, 2010 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. Quote Link to comment Share on other sites More sharing options...
qadir03 Posted December 26, 2010 Author Share Posted December 26, 2010 Ok, used the following diagram and connected to the red/black wire behind the 280z tach and works like a charm. Quote Link to comment Share on other sites More sharing options...
Hardwyre Posted January 9, 2011 Share Posted January 9, 2011 Ok, used the following diagram and connected to the red/black wire behind the 280z tach and works like a charm. 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? Quote Link to comment Share on other sites More sharing options...
qadir03 Posted January 10, 2011 Author Share Posted January 10, 2011 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? 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! Quote Link to comment Share on other sites More sharing options...
Hardwyre Posted January 10, 2011 Share Posted January 10, 2011 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. Quote Link to comment Share on other sites More sharing options...
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