OK, It's been discussed to death but I am having an issue with my tach after the 280zx electronic dizzy conversion on my 72 240z with an auto. I think all is hooked up properly but here we go.....

the green wire that was hooked to the ballast risistor is hooked up to the + on the coil. So are both of the b/w wires and the one wire going to the "B" on the module.

The - on the coil is hooked up to the "C" on the module.

The tach does nothing and was working before. I have read a couple post here and on other boards that say that you need to hook the b/w that is hooked to the coil and that when removed makes the car die to the green. then do these just stay not connected to the coil +?

I read somewhere else that said they hooked the tach to the coil -.....this doesn't seem right. Any sugestion? Oh, the car had dual points factory if that makes a difference.

Thanks!

First off, did you swap the original 240 coil to the ZX coil? You'll want to as the original 240 coil isn't designed to run on 12v all the time (or at least that is what the mechanical guys insist on). If you did NOT, then you may have other problems (rough running at higher RPM's) due to the decreased voltage to the coil and hence the E12-80 module, since the original 240 coil requires the resistor.

If you DID swap the coil, then all you need to do is plug the Tach back into the circuit. By having both the Green/White and the Black/White wire connected to the coil, you've completely disconnected it.

The Green/White and ONE of the Black/White wires are supposed to connect to the Resistor, and are the sensing portion of the Tach's circuit.

To determine WHICH one of the Black/White wires to connect, do a simple continuity check between the Green/White and the Black/White wires. Only ONE of those two wires will complete the continuity check (as long as you still have the Tach connection in place). The B/W wire that has continuity is the one to then connect to the Green/White wire, if you are removing the Resistor from the circuit, or to the ends of the resistor if it's staying. That's it. The Tach should now work as before.

HTH

E

Thanks for the clarification. All is working now. You guys are awsome......

Tach and all? Excellent, but more probably due to your perseverence than my post.

In re-reading my post, I may have introduced some confusion into the mix.

The B/W wire that does register continuity with the G/W is the one to connect to the + side of the coil, the one that does NOT is the one to connect to the G/W wire. That connection is required to provide power to the coil in the RUN position. In the START the coil receives power via the B/W wire directly from the Ignition Switch.

In checking the wiring, you apparently did the right thing and hooked it up correctly.

I'm posting this to ensure others who may read this get it working right the first time.

Sorry for the mix-up.

E

It's all working....I had the two B/W wires switched. All works now. The post I was reading about the dizzy swap actually had you connecting both B/W and the G/W to the + of the coil.......I corrected that and inverted the B/W wires at first. It works well now that I got the B/W wires corrected. Thanks for all the help!