I chased down a apparent short circuit to the alternator. It's a CS130.

Here's the scoop, I disconnected the negative battey cable and put a light bulb from the cable to the negative battery terminal. With all interior lights out, radio clock disconnected, engine computer disconnected, the light was still on. I ended up pulling the plug off the back of the alternator and bingo, the light goes out.

Narrowing it down further, I found that the short is on the F terminal. If connect a single wire from the F terminal on the plug to the F terminal in the alternator socket, the light bulb goes back on.

Is this really a problem (before I yank it off and take it down to be tested)?

EDIT: I just noticed something else. As I connect/disconnect the plug to see the light going off and on, I can hear a very faint, but very high-pitched noise coming from the alternator. I have to put my ear pretty close to hear it. But it's definitely audible.

 

sounds like the diodes are bad. depending on how bad it is, that will drain your battery in anywhere from a few days to an hour or two.

with everything turned off & plugged in there should be no sounds from the alternator.

 

I have this exact problem with my 88 tpi 305. Now I purchased a brand new alt and it still is showing a draw with the plug in and it makes the same sound. Im trying to trace the brown/white wire from the alt plug which seems to always have power, maybe making a ground in the alt? The wiring diagram says this wire goes to the fan fuse in the box, pulling this does nothing for me. Still a drain.

Any help?

 

I dont' know. I replaced my alternator and problem solved.