Help with factory alternator harness on '72 240Z

[RJK]

32 minutes ago, SteveJ said:

Stop and focus. I'm guessing that you're worried about making another mistake, and that's keeping you from reading carefully.

From my previous post, "with the key in OFF, you should have an open line on the L or "lamp" wire on the T plug to the white wire, and it should have continuity when the key is ON. That is because it is a switched source."

S - Sensing battery voltage. When the battery voltage drops, the voltage regulator excites the field to raise the output voltage of the alternator.

L - Lamp: On a lot of old cars, there is a light to indicate a charging failure. Under normal conditions, the voltage is the same on both sides of the light. When the alternator starts to fail, the voltage drops on the alternator side, and the bulb lights up. When the car is off, the alternator is not producing any power (and therefore no voltage), so if you are not using a switched source, the charging light would be lit all of the time.

By the way, these are the alternators I'm used to playing with. The alternator is inside the red rectangle. This one is a 16 cylinder engine with quad turbos. It will put out over 2 megawatts of power. The usual voltage output is 4.16kV to 14.4kV.

Thanks Steve. I literally read this post 5 times, so I am doing my darnedest to deduce the alternator labeling. I'm trying, I swear! This helps me understand what the L and S terms mean, relative to the internal wiring of the car. That part I have a solid grasp on. It's translating these terms to the language used on the ZCarDepot site's literature for the alternator that I am attempting to confirm.

From your language, I gather that the ZCarDepot labeling one pin "Ignition Key On" should tie to the L wire, internal to the car, correct? Since the ignition key would be switching on and off, and, the L wire is a switched source, right?

 

And what the ZCarDepot labels "to 12V post" would be the S wire, since to quote your post, the S senses the battery voltage, correct?

[SteveJ]

That is correct, provided that ZCarDepot identified the terminals properly. From what I can tell, they did.

https://trans-sen.en.made-in-china.com/product/VSGJimnPJKWj/China-Alternator-for-Nissan-Almera-X-Trail-2-2L-Mitsubishi-A3TB0771-.html

[SteveJ]

An interesting aside, I was looking at various wiring diagrams for the Frontier, and I noticed that the wire from the battery is still white and the wire from the ignition in ON is still black/white (shown in a different diagram). Granted a lot of other wires have changed, but they have kept some of the basics the same for a long time.

Note that there is a black rectangle by the S & L on the alternator in the drawing. That shows the orientation of the clip. Rotate that 180 degrees, and it looks like the one in the picture in my previous post.

[RJK]

Welp, I don't know what I'm doing wrong here, but I obviously have something wired improperly. When I try to fire the car, I get no cranks, and all lights go blank. With the key at the accessory position,  lights come on, and I hear the fuel pump run. Everything goes immediately dark if I try to start. Here's my specs:

-all fuses have continuity

-new starter motor

-proper motorsport auto 6 pin adapter for internally regulated alternator

-battery on trickle charger for 3 days straight; reads over 13V once removed from charger

I'm sorry to be the problem child here;  really stumped here. Any help appreciated.

[Yarb]

Can you start the car by jumping the starter solenoid and the key in the on position.

[SteveJ]

11 hours ago, RJK said:

Welp, I don't know what I'm doing wrong here, but I obviously have something wired improperly. When I try to fire the car, I get no cranks, and all lights go blank. With the key at the accessory position,  lights come on, and I hear the fuel pump run. Everything goes immediately dark if I try to start. Here's my specs:

-all fuses have continuity

-new starter motor

-proper motorsport auto 6 pin adapter for internally regulated alternator

-battery on trickle charger for 3 days straight; reads over 13V once removed from charger

I'm sorry to be the problem child here;  really stumped here. Any help appreciated.

I'm not sure what lights you are referring to. 

When you place the key in start, the white/red wire going to the ignition switch connects to the green/white wire and the black/yellow wire.

The green white wire goes to the tachometer and comes out black/white. The black/white wire goes to the coil positive.

The black/yellow wire goes straight to the solenoid to engage the starter. There should be a spade connector on the solenoid to plug in the black/yellow wire.

I can see the black/yellow wire going to the solenoid in you last photo, but the solenoid is partially obscured by the heater hose.

Here is the solenoid power connection in my cars. In the first photo, the solenoid wire is the blue/yellow wire with the insulated connector. In the second photo, it is the yellow wire with the insulated connector and black insulating sheath. The smaller gauge red wires are for my headlight relays.

I suggest setting up your voltmeter to verify you have voltage at the black/yellow wire when the key is in start.

 

[RJK]

Occams razor reared its' head on this one, I think. The problem was the battery....I replaced it with a new battery, and the car cranks fast and strong. When I saw the voltage reading, I assumed it was sufficient, but it doesnt look like it could move enough amperage fast enough to turn the engine over. Thanks so much for your help folks!