[Shotimes] Intermittent alernator failure on '93 ATX?

[Tom Leeth]

Has anyone on the list ever seen an intermittent alternator failure on a '93
SHO ATX (120 Mitsubishi alternator with internal voltage regulator).  Symptoms
have occurred twice now.  First time about three months ago and again this
last weekend.  Symptoms are: (1) battery light comes on hard, (2) EATC head
unit, A/C compressor, and engine cooling fans shut down at same time battery
light comes on,  (3) a relay (or thermal overload device?) in or near the EATC
head unit clicks (shutting down voltage to the unit?),  and lastly the air bag
warning light lights with a two blink pulse, but the two pulse pattern happens
more or less randomly (not continuous). Car runs OK other wise.   I didn't
have a voltmeter with me on either occasion to check alternator output when
the battery light was on.

On the first occasion when I got the car home, the battery was puking
electrolyte.  I pulled the battery and the alternator and had them checked at
local auto parts store(s).  Both tested OK.  I assumed that the battery had
had an internal short (plate-to-plate) that was jarred loose during removal
and handling.  After cleaning up the mess under the battery tray and putting
everything  back together, the car ran and functioned normally.  After a few
days of driving the car with no problems, I put in a new battery as an
insurance measure.

On the second occasion (about 1000 miles after the first),  the symptoms
reappeared but no puking battery this time.  This time I was 15 miles or so
from home and as I drove home the symptoms cleared briefly only to return.
About 5 miles out the symptoms cleared completely.  I checked the alternator
output before I shut the car down and it was OK (13.75 VDC).  I drove the car
last night and everything was normal.

Sorry for the long winded question, but have any of you ever seen the internal
voltage regulator on the Mitsubishi alternator fail and then recover?  Since
its a solid state device, I'm not sure how that can happen.

Thanks for any advice you might offer.  I don't mind replacing the alternator
if that's the problem, but I would like some proof its bad.  My plan now is to
keep a voltmeter in the car and when the symptoms show up again, check the
alternator output.

Tom Leeth
'93 ATX with 94.5K (original owner) miles