Okay, I have dug around, searched, tested, looked at wiring diagrams, and even asked AI and I am stumped. I have a mystery .2A draw with the ignition off on my 1972 240z. I did this conversion a while ago https://www.classiczcars.com/forums/topic/46888-240z-alternator-upgrade-instructions-w-pictures/#google_vignette

The car charges and runs fine, but it draws power when turned off. I have checked each fuse and no change, I have pulled the main charging cable from the alternator and no change. When I unplug the plug from the back of the alternator (yellow / white-black) the draw goes away.

Testing the wires in the plug that used to go to the voltage regulator I get:

• Yellow is connected to the plug in the alternator

• White-black is connected to the plug in the alternator

• White is always live

• black-white is on IGN

In the plug that connected to the voltage regulator I had black-white connected to white-black with the stripe on the white-black side I have yellow connected directly to white. I have tested the diode, and it looks fine.

I am kind of at a loss of what to check next. Any thoughts?

What is the build date of the car?

Can you have someone else unplug and plug in the T connector on the alternator while you listen for a relay clicking in the passenger footwell?

Build date is 8/72, I can try listening for clicking tomorrow - assuming this is looking for the fuel pump relay that needs the yellow wire clipped is that correct? I looked for a relay and didn't see one, but it could be tucked somewhere and I will try listening to see if that gives me any clues.

That build date would typically indicate a 73, though some states may have titled an 8/72 as a 72 back then.

https://jdm-car-parts.com/blogs/news/vin-verification-of-us-datsun-240z-260z-280z-280zx?srsltid=AU7gw4VZKuT31B6faCZYskqAm_f9DiAZx3ONK3Xsnn_scBm8EpKTCGA-

Oddly, my vin is only 5 digits so that link says it is a 72, but the door panel shows 8/72. Either way I am now looking at 73 wiring diagrams to see if that changes anything.

North American VIN’s for 73 model year S30 start at 120000. The 72’s started at 40000 IIRC. 5 digit vin pretty much makes it a 72. There was lots of factory delays and weird goings on that could very well make a 8/72 a 72 MY and not a 73. Do you have a lit HVAC panel or front bumper with a filler strip and massive mounting bars? Those are hall marks of a 73.

No NA S30 had a electric fuel pump, though all were wired for it. There was a factory relay setup that was part of a factory add on setup that installed an electric fuel pump and a new harness that detected if the car was still running in case of an accident. Extra 2 relays that got mounted passenger side kick panel and lovely harness out to the engine bay taping into the Vreg connector I believe.

4 hours ago, bingo said:

Oddly, my vin is only 5 digits so that link says it is a 72, but the door panel shows 8/72. Either way I am now looking at 73 wiring diagrams to see if that changes anything.

Unfortunately, the 73 wiring diagram won't show it, either. It was added on later. Download this file and look at the mounting points for the relays: https://www.classiczcars.com/files/file/60-fuel-system-modification-plus-73-74/

Also, is the hazard switch a pull switch or a toggle switch. 73 was the only year for the pull switch.

1 hour ago, zKars said:

North American VIN’s for 73 model year S30 start at 120000. The 72’s started at 40000 IIRC. 5 digit vin pretty much makes it a 72. There was lots of factory delays and weird goings on that could very well make a 8/72 a 72 MY and not a 73. Do you have a lit HVAC panel or front bumper with a filler strip and massive mounting bars? Those are hall marks of a 73.

No NA S30 had a electric fuel pump, though all were wired for it. There was a factory relay setup that was part of a factory add on setup that installed an electric fuel pump and a new harness that detected if the car was still running in case of an accident. Extra 2 relays that got mounted passenger side kick panel and lovely harness out to the engine bay taping into the Vreg connector I believe.

Two wires were tapped: the neutral (yellow) wire between the VR & alternator for the fuel pump relay with the normally open contacts and the black/yellow wire for the starter solenoid was for the fuel pump relay with the normally closed contacts. The tap for the neutral was actually small harness Nissan designed to go between the VR and engine harness. I pulled it out of my 73 a long time ago.

It has a toggle switch for the hazards - another confirmation that it is a 72. There are no relays and I can't see any evidence of an additional harness for the relays.

Any other ideas of what to look for? My charge indicator light doesn't seem to work if that is any indication - are they even on 72s? - I got mixed results searching for this and didn't see it in the wiring diagram.

15 minutes ago, bingo said:

It has a toggle switch for the hazards - another confirmation that it is a 72. There are no relays and I can't see any evidence of an additional harness for the relays.

Any other ideas of what to look for? My charge indicator light doesn't seem to work if that is any indication - are they even on 72s? - I got mixed results searching for this and didn't see it in the wiring diagram.

No charge indicator light.

What is the voltage at the battery when the car is running? I'm wondering if there might be an issue with the internal voltage regulator. Remember that new does not always mean good.

I couldn't find the charge indicator on the wiring diagram, and I can't see an indicator in the ammeter so maybe 72's don't have them? I couldn't find conclusive info on this online.

I get 13.5 V when running it is pretty consistent, not bouncing up and down. It does go up a bit at higher rpms and down a bit at lower rpms, but the whole range is from 13.4-13.6. It seems to charge fine.

I fixed the issue in a non-conventional way - is this crazy? Since white is always live that is the only place the leak could be coming from (and disconnecting the jumper got rid of the leak) so I connected black-white to the diode that goes to white-black as was instructed in the tutorial and then I connected black-white to yellow with a wire (instead of yellow to white). The voltage looks identical, so does the ammeter reading after doing this. The only difference is that now my load goes down to virtually 0 when the key is off.

Thoughts?

There is an issue with the VR in the alternator.