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LR160 alternator swap problem on 73 240Z


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So after the discussion we had here about swapping in an L28 LR160 alternator in order to do away with the 240Z voltage regulator I went to Zhome as instructed and followed the instructions word for word. THey are in short:

Get LR160 (mine is off of an '81 280ZX)

Get matching (longer) fan/alt belt

Unplug v.regulator

On the engine wire harness side of the v.regulator connector connect:

_ the white wire to the yellow wire

_ the black/white to the white/black

_ and don't do anything with the remaining black wire.

_ it didn't say anything about the condenser that was grounded with one of the v.reg mounting 10mm bolts so I left there - still grounded.

reconnect the wires that go to the alternator as per normal, ie:

_white/red goes to "A" ("BAT" terminal)

_ black (ground) goes to "B" terminal along with the condenser that was there to begin with.

I started the car and checked that voltage was not in excess of 15.0V and everything appeared fine... BUT:

So what's my problem?

I turn the key to the off position but the car continues running!!

What did I do wrong?

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I'm confused....

I just went and re-read the directions and the only thing I can think of is it has to be something in the black/white stripe and white/black stripe connection as it is the only connection that goes to a switched power supply... :ermm:

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I re-read Carl's (Bambikiller240) post on my other thread here in the Help Me section and he does briefly mention that in addition to doing the wiring thing you need to insert a diode. But he does not specifically say where or how?

Are all diodes created equal? Do they have ratings or different sizes they come in? How do I describe the one I want when I go to Radio Shack and more importantly where do I put it?


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hmm... my reasoning behind it is very simply nothing more than to remove something out of the engine bay (ie v.reg) to make it cleaner in appearance. Yes it really is as shallow as that.

So tell me Daniel do you know where I ought to be putting this diode?


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Having never performed your task the diode question would require some study on my part.I have no doubt this can be done.The results as I see it are you wind up with a non-standard wiring system that only you will kinda understand and increased the cost of replacing your alternator.As far as cleaning up under the hood,odds are only you would notice.Although sometimes thats enough!!

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I have had the exact problem and yes, you need a diode. I have the details written up in a text file that I cannot get to right now. If you go to zcar.com and search using zx alternator and diode you will probably find it. Basically, you need to wire a diode so that current from the top of the "T" connector on the alternator cannot bleed back to the ignition. If you can't find the details by searching zcar.com, email me back and I can get the info for you. It might take a few days.

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I found this correction info on ZCar.com. It contains info from the author of the ZHome article that I refered you to. It exoplains the correction that you need to do to fix your problem. Good Luck, Carl


from ZCar.com archives:

The alternator you want will be from 78-280 or 79 and up 280zx. Internal regulated. Others likely from same year 810's or Maximas. Likely other Datsun/Nissans from same general years will work also. Go to Zhome.com and look under 'Index of Technical Articles' then scroll down to 'Engine' and under that find '280 alt. in early...' When you do this you may need to add a diode so the car will shut off after it is started. If so add this email response from Golik:

Because of a minor wiring difference between late and early 240Z's, this

can occur. However an electronic component called a diode can be used

to prevent this. Obtain a 1N5062 (or equivalent) from your local electronics

supply company. A diode has two leads, an anode lead and a cathode lead.

The cathode lead is identified by a band near that lead.

The diode can be mounted on the "dummy regulator" connector.

Recall that Step four of my instructions was:

4. Connect the black with a white stripe wire to the white with

black stripe wire. This connects the "L" terminal to a switched


This should now read:

4. Connect the anode of the diode to the black with a white

stripe wire and the cathode of the diode to the white with

black stripe wire. This connects the "L" terminal to a switched

12V supply through the diode preventing reverse current from


Good luck

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About the Diode:

Radio Shack does not carry it

MarVac does - their part number NTE506 costs a whopping $1.65

Fry's Electronics also carries it.

About the alternator:

The S130 pulley is no more than 1/16" different in diameter than the S30 unit. The difference lies I think in the Alt housing which does offset it a bit more from the engine. I tried to reuse the L24 fan/alt belt but it just wouldn't work - thus the S130 non-turbo one.

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