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sid240z

Ka alternator wiring questions

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I have a 73 240z witch I'm currently swapping a 95 ka24de into and I have most of my wiring done, but I was wondering how do I wire the ka alternator to work in my Z? I've searched it and i can't seem to find a answer. I would greatly appreciate all the help I can get

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I just got my SR running a few weeks ago, and my one remaining issue is that my alternator is making ~15.5 volts. I assumed the voltage regulator was just bad and started looking for another, but then I found this thread :

 

http://community.ratsun.net/topic/54092-alternator-wiring-on-sr20-install/

 

I had left the second (smaller) wire off the 2 pin plug disconnected. The larger wire is the voltage sense and I put that the power as you said. The smaller one though, apparently, usually runs through the dash charge light or a ~100ohm resistor to 12v. Apparently the alternator actually sources some kind of reference from this line or some such? I don't know. I found several other rather cryptic references to it needing to be hooked up.

 

I couldn't find a resistor but I found a few old bulbs so I'll see later this week what happens when I hook that up.

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There are some pictures and test descriptions here - http://www.nicoclub.com/nissan-service-manuals and here http://www.nicoclub.com/datsun-service-manuals depending on what car and alternator you're working with.  You can even check that you don't have S and L reversed.

 

And no need to hack-job it with stray bulbs and resistors.  Your car probably has a charge lamp circuit that will do the job. 

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I used one of the small lamps that was actually the backlight for the original 240z gauges (read about 20ohms). Hooked that up to the second smaller wire off the alt, other side to positive. This brought my idle alternator voltage from 16.X down to 14.7 so all is well now. Seeing as that works I'll probably pick up a 1-2watt 20ohm resistor and be done with it.

 

Big wire of the 2 pin plug to live, small wire to live through a bulb or resistor (20ohms worked for me, if you use a resistor use something that can handle a bit of current).

 

Like many people I'm running a full custom wiring job and aftermarket gauges. We don't have the luxury of our car "having a charge lamp circuit that will do the job". My comment was intended to be helpful to that crowd as I was having trouble finding the info I needed.

 

Here's a picture of my hack-job of spare bulbs and resistors, for the kind gentleman above :)

 

IMG_20140703_202726070.jpg

 

 

IMG_20140905_185637572-1.jpg

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Looks nice.  I was just being blunt to make a point.

 

I think that you have your S and L backward though.  A disconnected L would have stopped the alt from charging at all, unless you revved the engine first.  A disconnected S, that would have caused your symptoms.  You don't need a bulb or resistor on S.  And the bulb's main purpose on L is to indicate what the voltage regulator is doing.  Just saying, S is for sensing voltage so it can be controlled, which is what your problem was.

 

For future readers...

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