4amp draw- high pitched whine from engine compartment- ignition off

[gluaisrothaii]

I was following this when it seemed to be resolved. Food for thought:
...



With the original alternators, the Brown wire is normally connected to AUX #2 Relay. Using the same terminal, it also feeds the BATT light via a Green wire through Fuse #5.
(! not 4, 6, 10 ???)

I'm suspecting PO mods e.g a radio's Always Hot Power/Memory wiring for the radip etc crossed up....Something feeding the regulator on a common circuit... Maybe see what happens if fuse #5 only is pulled.

(I'd jump the sense wire to the Main Alternator post, if not using the Brown wire even though all of the alternators I've seen so far with the feature have it virtually connected internally....)

FWIW-
Make sure the BATT bulb is correct. The wrong incandescent or a LED causes problems.

When you hear the sound, look VERY carefully at the BATT light for a faint glow.
If it does, the little diode trio/regulator in the alternator may be getting zapped...or defective Alternator #2.

All wiring is stock/original. It was an untouched car when I bought it. The alternator bulb is incandescent, as it should be. The alternator charges perfectly when the engine runs, stable smooth DC at 14.4/14.6 V. Just occasionally turns itself on when it shouldn't. I'll look at the bulb in the dark next time I hear the whine.

What I can say is that it takes very little voltage to activate the regulator. I was able to turn it on with .3Vdc. Seems like it should take more than that.

I guess this is why most aircraft use an externally regulated alternator with a split master switch which allows the alternator to be controlled independently of the main bus.

[gluaisrothaii]

A lot of rebuilders take short cuts. They may look for broken coating on the windings, pry apart what they can see and just re coat what it visible instead of actually rewinding the rotor.

A good rebuild will be with fresh windings.

It's a brand new CS130 from DMCH. Two in a row now.

[Ron]

It's a brand new CS130 from DMCH. Two in a row now.

Pull it and take it to an auto parts that load tests (AutoZone does, around here anyway). It takes very little to pop the regulator or trio in those units (and several others). I can't count the times that customers reported problems immediately after simply giving someone a jump or using a cheap charger on their own vehicle in our rebuild shop...