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73 240Z Wiring


Tiny Z

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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.

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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 by zKars
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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.

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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.

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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.

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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

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

post-21373-14150824523705_thumb.jpg

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

post-21373-14150824524203_thumb.jpg

Edited by Captain_Zeros
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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.... :)

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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.

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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.

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Six shooter, not all 73's had 4 wire tachs. There is thread a few years ago where I too made this statement but was put in my place with clear real examples of late 73's getting the 3 wire tachs. Not common, but they are out there.

TinyZ, I'll send you an PM about the harness.

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Sorry to go off on a tangent... but...

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.

Looking through my '74 PDF it seems to confirm the opposite:

1974 FSM page BE-33:post-21373-14150824531386_thumb.png

On page BE-37 in the '74 book it also states "this tachometer is a voltage trigger type" (as opposed to the current trigger early tachs) except they seem to have recycled the old 4 wire art. Hmmm.....

Also, all things considered, my tach has the early 7k redline face and from pulling it apart it didn't seem to be face-swapped from what I could tell, nor was there wiring harness in place for a four wire tach, leading me to believe the 3 wire tach was a mid-year '73 change at least on some cars. Late 73s have all kinds of little undocumented features in the electrical systems. (which is why I make a point of having a '72 FSM and a '74 FSM laying around at all times :cheeky:)

Edit: my car is a June '73 build date, if that is relevant to anybody in the future (or present) reading this thread

Edited by Captain_Zeros
data!
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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.

All 260Zs came with 3-wire, voltage-triggered tachs (with a 7k RPM redline).

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  • 1 month later...
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.

Listen here "WADE" I suggest you take your high horse and ride back over to zcar.com. Youre adding to the problem you fascist. you should just sell your car "WADE" because you cant take it with you when your old arse dies. The man asked a question for help, and he probably gets a lot of people like you! you make me ashamed to have a 240z.

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also to tiny z i have an uncut 1972 engine harness, i see you dont want to buy.. but ill stilll have it. here is a diagram for early cars i found on here a while ago post-29456-14150824844112_thumb.jpg

Edited by Nobsz
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also to tiny z i have an uncut 1972 engine harness, i see you dont want to buy.. but ill stilll have it. here is a diagram for early cars i found on here a while ago [ATTACH=CONFIG]64618[/ATTACH]

That is for an early Z. There are differences between that one and the wiring for a 73.

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Listen here "WADE" I suggest you take your high horse and ride back over to zcar.com. Youre adding to the problem you fascist. you should just sell your car "WADE" because you cant take it with you when your old arse dies. The man asked a question for help, and he probably gets a lot of people like you! you make me ashamed to have a 240z.

Cool your jets, man. Just let it go, it's not adding anything to the discussion to get upset about a post and then look for a fight, and no need to call anyone names or anything here.

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Actually, IMHO, Wade was not far off the mark. The OP stated in his initial post that he didn't understand much of what he was doing and that he was looking for a shortcut.

I try to minimize jury-rigging wiring in the car. The modifications I make tend to be things like adding relays to the headlight circuit or bypassing the obnoxious seatbelt interlock relay. I wasn't going to offer any advice myself, but when the OP asked about an engine harness, I directed him to a potential & reputable source.

I will try to help people with electrical issues online and on the phone. However, I would agree with Wade that if you have little knowledge of automotive electrical systems and want to ignore all of the work the Nissan engineers did during the design & production of the car, it would be best to seek the services of a professional.

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