Condenser on 280z Alternator

[28Zero]

Howdy. My alt has an internal short, showing battery voltage across the fusible link connectors (link removed), and so I got a new one after a test showed that the internal diode was bad. Connected the new alternator up as in the pic. Again, it showed the same internal short across the fusible link. ARGH. help? Is it possible that the condenser is at fault and how/where do I get a new one if it is?

Thanks!

[Zedrally]

Condesers go open circuit when they fail.

Why not test it by disconnecting it, FWIW, I don't see it as your problem, more likely that the alternator you have swapped out is faulty.

[28Zero]

I took in the replacement alternator in and it was dead as a doornail. ARGH! I got a car show tomorrow I was hoping to take the car to!

So there's no inherent problems with wiring up the alternator like the above picture? Nothing that should cause a short? After I hooked up the alternator and then connected the negative battery cable to the battery (positive was already connected) there was a small spark.

Tested the condenser with a multimeter: white/red wire to condenser: ~12v quickly going down to below 2 volts. black (earth) to condenser ~12v going down to .2v; so it would appear that the condenser is fine?

[28Zero]

Perhaps I'm not following the right procedure in hooking up the alternator wires? should I touch the condenser to the ground wire before screwing on the ground and condenser onto the same post? Should the ground go on before the power wires? Also, I'm not exactly sure about the blue wire of the "T" connector. Could the blue wire cause the short?

Is leaving off the condenser a possibility? I don't understand the role of the condenser in this situation. Haynes, Chilton's, Clymers and the two automotive electrical books I got don't have anything on this.

(Been trying to solve this short off and on for the last two months!).

[28Zero]

Ok, I measured the voltage difference between the blue wire of the "t" connector and the positive power wire and it's 12.04v (battery voltage), indicating that the blue wire is grounded or shorted, correct? This blue wire leads to 1) fuel pump relay 2) through C-4 to brake warning lamp relay 3) through C-1 to volt gauge. I don't see any ground wires attached to the blue wire on the schematic. Pulled fuel pump relay, connectors C-4 (white) and C-1 (blue), and there was no change in the voltage difference.

Right now I'm checking the actual wire condition & splices of the blue wire.

[sblake01]

Your hookup looks basically the same as both of my cars except that my condensers are mounted on a seperate stud, above the "E", rather than with the black wire.

[beandip]

I dont know about the 280Z , but in the past the condencer is for a static suppresser for your radio . Just take it off.

[28Zero]

Interesting. I'm hesitant to take anything off unless I know what it's for. If it's a static suppressor for the radio, what's it doing on the alternator?

Am I correct in assuming there's a short with the blue wire? I don't want to blow another replacement alternator!

Cheers,

James

[Arne]

The condenser on the alternator is there to eliminate alternator whine in the radio.

[28Zero]

Well, it was indeed a short in a component on the blue wire: the volt meter. So i've been taking apart the dash trying to get to the volt meter connectors. :stupid: So much fun, I'm going to bed.

Cheers!

[28Zero]

Well, I'm stumped. After taking apart the dash to get to the voltmeter & unplugging that, it didn't solve anything. So today I went back at it, only to determine that the short goes away if I unplug the Fuel Pump relay or the Fuel Pump control relay. The blue wire goes to the control relay, through a 62ohm resistor to the white/black stripe wire that goes to the fuel pump relay, through another ~64 ohm resistor and then to the ground wire.

So it seems that the blue wire which is connected to the positive wire (via the alternator) goes through two resistors (via the relays) and then to the ground. Isn't this a permanent short then? Or am I totally off in reading this wiring diagram?

Cheers,

James

[28Zero]

Sorry, I meant "coils" instead of "resistors".

anybody have a clue? I'm at a loss to even figure out what to check next or if I need to replace a relay. If I do need to replace a relay, which one?

On a semi-related note, if you have a manual '78 like I do, and if the wiring diagram is right, it appears that the Fuel Pump Control relay's WB wire (upper right hand corner next to the L wire) goes through the firewall to the C-4 connector, splits apart with one going down to a small connector, becomes the G73 wire which then goes back across the firewall and goes to the EFI main relay, right next to the Fuel Pump control relay!

Seems like this could be simplified.

Cheers,

James