Alternator help needed

[Pichuki]

Hello I'm new to the site. I was wondering if anyone could help me with the fallowing issue I'm having: I bought my first z (83 280zx) last month and the alternator was overcharging. I went and got a new one, and I tested it before installing it on the car, and it was good. Now for some reason I think somehow put thenwires on wrong. There is a white cable wich is the positive, and off that there's a thinner one. That thinner one runs to a little cylinder like thing wich is grounded to the alternator.Then the is a harness wich has two wires on it. As soon as I started the car smoke came from this conector and it melted ... Can anyone assist me with any info, I would greatly appriciate it.

[beandip]

Hello I'm new to the site. I was wondering if anyone could help me with the fallowing issue I'm having: I bought my first z (83 280zx) last month and the alternator was overcharging. I went and got a new one, and I tested it before installing it on the car, and it was good. Now for some reason I think somehow put thenwires on wrong. There is a white cable wich is the positive, and off that there's a thinner one. That thinner one runs to a little cylinder like thing wich is grounded to the alternator.Then the is a harness wich has two wires on it. As soon as I started the car smoke came from this conector and it melted ... Can anyone assist me with any info, I would greatly appriciate it.

I am not sure what you have done. The cylinder thing is a capacitor for static suppression for your radio. The White/red stripe is the power lead, +. My Z is in storage and away form my home at present so I cannot go and look. It's been a while since I did what you are doing and I cannot remember all of what you are dealing with. It should be a straight forward install.

[SteveJ]

Download the FSM from here. The file should have a wiring diagram. Also check the Engine Electrical section. There you will find the correct wiring for your alternator.

The little cylinder is a condensor. It shouldn't be getting 12 VDC+. If it did, you're doing something wrong.

[FastWoman]

Steve, actually the wire of the noise suppression capacitor (condenser) would be +12 and connected to the output post. The body or can of the capacitor would be ground and would be connected/bolted to the alternator.

I had looked at this thread earlier, and I haven't a clue either. Ordinarily both of the smaller wires would be fed 12V. One is the voltage reference line, and the other is the alternator fault light line. The fault line is grounded when there's a fault with the alternator, thus grounding the fault light in the dash. (The other side of the light goes to +12).

Is it possible there's an alternator fault AND the fault light is miswired? Perhaps you have +12 going directly to the fault line, sans a bulb?

Anyway I wonder whether your alternator is still good. What you describe makes no sense otherwise.

[Pichuki]

Thank you very much guys I really appreciate the information, I think I came to the conclusion, that the small harness that has a positive and negative wire was faulty. It wasn't making a good connection so it was causing a
bad connection and it would melt and smoke.

[SteveJ]

Sarah, I stand corrected. As you stated, the condensor is off the positive. If it burned up, there is the chance that the condensor is bad and grounded out. Just because it's new doesn't mean it's good.

Ariel, the EL section has what you need to know about the alternator starting on page EL-18.

[FastWoman]

The thing is, though, the little connector for the voltage ref and alternator fault light melted. I don't think it would have anything to do with the condenser.

OK, I'm now looking at an internal schematic of the '78 alternator in the '78 FSM, page EE13. If you were to ground terminal L of a running alternator, you'd have a direct short and would probably melt the connector. I'd check there.