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280zx Alternator Upgrade for 1975 280z Help! (Infamous Missing Green/Red VR Wire)


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Hello all, I have searched low and high to no avail. I am upgrading to a 280zx alternator in my 75 280. I was following the diagram below and carried out with the white to yellow but had noticed that my volage regulator did not have the specified green and red. It appears that the pin hole of the voltage regulator for the G/R was capped from the factory. So I am hoping that there are some guys here that have figured something out for the 75s that could help me finish this up? 

 

Thank you in advance...

75.gif

Connect 1-5 
(lamp to windings common) green&red to white&black
 
Connect 2-3 
(+12V to Sense)                 white to yellow
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Post a picture.  And, to be clear, it's not the VR that has G/R wire it's the car's wiring harness.  And make sure you're not looking at the plug upside down.  Go by location, not color.  Check the diagram in the FSM, Body Electrical.  Look for blue like 1976 as an option too.  

 

When you're done, search for "brake warning lamp check relay" if your battery starts dying when the car sits for a few days.

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Yeah I mis-worded that. The only wires that are in the harness leading to the voltage regulator is ; green, black, white/black, yellow, and white. The FSM for the 1975 does have the green and red going into the ign interlock unit but my vehicle does not have the green and red nor the ign interlock unit. I have read about this specifically for the 1975 only. 

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It might be that your 75's ammeter uses a different wiring scheme.  Someone with a 73 or 72 just had a similar problem.

 

You could just use a voltmeter to find what the ZX alternator needs at the T plug, S(sense) and L(amp), and go from there.  The only one that you really need the VR plug for is L, it would be switched power. Find L on the wiring diagram and use that for L on the alternator.  Use the meter to be sure it's switched power.  S just needs to be at the battery or a point on the system's positive circuit, but one of those wires is probably always hot so would work..  If your alternator isn't marked with L and S you can probably find a diagram in a ZX FSM.

 

And as I mentioned, power for the brake check relay might also come from the external VR.  It does for 1976 and it can cause problems.

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The only wire I have to work with from the original harness going to the regulator would be the solid green which routes to the tach, "switching module", floor temperature relay, and the "checker". From what I recall while searching where the green wire went into my cabin it appeared that the previous owner had cut it. Would this wire work for the L(amp) connection of the alternator?

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You had an external regulator with just one green wire running to its plug from the harness?  Can't tell what you mean.  L just needs to be switched, i.e. only has power when the ignition switch is on.

 

There's another description of how to get it done at the very bottom of the page you got your first drawing from.  atlanticz.ca.  If you don't have a voltmeter, a test light will work.  The new alternator just needs switched L for excitation, S to sense voltage, the big white wire to feed the fusible links and the battery via connection at the starter lug, and a ground (commonly though both the mounting bolts and a black wire).

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The external regulator had a white/black, black, white, yellow, and solid green. I have already followed the steps shown on atlantic z by connecting the white wire with the yellow wire. I now just need a wire that I can connect to the white/black wire coming from the L of the alternator. The write up says to connect it to the green/red wire that is supposed to be in the plug that goes to the old voltage regulator but I guess the 75 models did not have the green/red wire. So I am looking for an alternative at the moment. 

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