73 240Z Wiring

[Tiny Z]

I have no intent of buying any of the original wiring and i am trying to figure out how to get power to and from the coil to the distributor and how it should be wired. i have seen a couple of diagrams but they do not specify what cable goes where. I'm planning of having flip switches and that kind of stuff. Seems easier than investing on a expensive harness.

Thanks all help is Appreciated.

[Captain_Zeros]

What?

[zKars]

TinyZ:

First welcome to the Z obsession!

Is your current wiring harness really in such bad shape that you feel you have to replace it all?

The Factory Service manual for your 73 is available here. XenonS30 The "Body Electrical" (BE) section has the schematics and wiring connector layout diagrams you'll need.

I have to say that the effort to understand the current wiring, so that it can be replaced with new, and then doing that replacement, tends to be far more difficult and time consuming than taking the understanding you gained in part one (understanding what you have now) and just fixing those parts of your harness that need it. We call this the "painless wiring syndrome".... There ain't no such thing as a "painless" wiring harness replacement.

If your engine bay harness/dash harness is "that" bad, you might put an "want to buy" ad on here anyway. You might be surprised how affordable one can be if you ask. hint hint....

There also lots of electrical experts here that can help with specific questions.

After looking at the wiring diagram in the FSM, do some research on how points distributor systems work. Just doesn't get any simpler. +12 ignition on the "+" coil side, and the points make and break a ground to the "-" side of the coil six times per dizzy revolution to make it spark. That's it.

Edited June 12, 2013 by zKars

[Six_Shooter]

The only "difficult" part is if you want to retain the OEM tachometer. It's a current triggered tach that requires the ignition feed to the coil to be first connected to the tach and then from there run out to the dizzy to work.

I'm also curious why you want to change the way the vehicle is wired.

[Wade Nelson]

I'm gonna be the inconsiderate, unkind commenter here.

If you don't know how to correctly wire up a coil / ignition circuit without even LOOKING at wiring diagram, or don't know how to READ a wiring diagram for your particular vehicle and

figure it out...

You have no business "re-wiring" your vehicle and "adding flip switches and that kind of stuff." Someone else is just going to have to clean up your mess.

As far as "not buying" or not "USING" any of the original harness --why make it easy on yourself when you can build a new harness from scratch, wire by wire?

I suggest you go find an AUTO ELECTRICIAN and pay them to wire up your basic ignition circuits for you and call it good.

[Captain_Zeros]

The only "difficult" part is if you want to retain the OEM tachometer. It's a current triggered tach that requires the ignition feed to the coil to be first connected to the tach and then from there run out to the dizzy to work.

Actually my '73 240Z has a ground triggered three wire tach. Late 240Zs your mileage may vary with build date.

[Tiny Z]

The thing is that i bought it without a wiring harness. for the ignition wiring is not that i dont know how to read a schematic but that the schematics i have found do not specify where on the distributor its plugged up to. Thanks

[Tiny Z]

Thanks for info will look into the manual.

[Captain_Zeros]

A standard 1973 manual transmission distributor has a single male terminal here next to the condenser (which is towards the engine block when installed):

If it's an automatic transmission dual points distributor, it'll have a second connector, but I haven't messed with one of those myself.

If it has a big black box hanging off the side with a couple connectors, it's a later model distributor with (only very) slightly more involved wiring

Edited June 12, 2013 by Captain_Zeros

[zKars]

Whoa. No harness... As in none? anywhere? or just the engine bay?

I, for one salute your bravery and willingness to take on a challenge. Ignore the nay sayers and carry on.

Remember the harness offer....

[beermanpete]

The wire between the coil and distributor connects to the distributor on the back side. See the photo posted above by Captain Zeros. The positive side goes through the ballast resistor (assuming you still have points) and then to your on/off switch. It you have the 4-wire tach you need to have that wired in series with the positive feed to the coil. Bring a wire from the battery or large lug on the starter solenoid to power the ignition and other electrical loads you have. Make sure to use a fusible link or fuse with a suitable rating.

[Six_Shooter]

Actually my '73 240Z has a ground triggered three wire tach. Late 240Zs your mileage may vary with build date.

It's been swapped at some point in it's life. ALL '73s have the current triggered tach. The 280Z tach swap is a popular one, so I'm not surprised that it would be swapped in your car. Looking in the FSM for '74 looks to confirm what I thought that '74 also had the current triggered tachometer.