I'm using a 72 engine compartment wiring loom & an A15 coil & electronic distributor, so no ballast resistor which is fine.

The 72 wiring diagram shows the tach leads being fed off the ballast resistor - will this cause the tach to not work since the resistor isn't in the circuit anymore?

If so do I just plug the 2 resistor connections together to complete the circuit?


thanks, Evan

short answer is yes. You could identify which of those two wires has the +12v and simply connect that wire directly to the + side of your coil [as you are using electronic ign] and totally eliminate the loop cct for the ballast resistor.

Does your loom also have [typically black with red trace] wire that also connects to the +ve terminal on your coil which supplies the full 12 volts when engine cranking on startup. That cct bypasses the ballast resistor to make for a strong spark when starting the engine... Just thought I would ask.

Thanks Benny, yes the main + lead to the coil in the loom has a black/red wire & a black/white wire coming off the same spade connector going to the ballast resistor.

So your saying to take the "out" side of the ballast resistor wiring (another black/white wire) & connect it directly to the positive side of the coil input thus eliminating the ballast resistor circuit altogether - did I get that right?

thanks!

That is correct.

* You don't need the ballast resistor when using the newer electronic ignition coil

* You don't need to modify the wiring, or connect the two resistor wires together. Just connect one of them to the coil. The one that goes to 12V.

Compare to this diagram: Coil Wiring


The white wire is for aftermarket tachometer. With Datsun 1200 tachometer, use the wiring in the dash harness.