[Shotimes] Intermittent alernator failure on '93 ATX?

[Paul Nimz]

If the small wires that plug into the alternator are not making good contact
the alternator will charge unregulated.

Paul Nimz
'97 TR
'93 EG mtx


----- Original Message ----- 
From: "Tom Leeth" <tomleeth@charter.net>
To: <shotimes@autox.team.net>
Sent: Monday, September 01, 2003 11:53 AM
Subject: [Shotimes] Intermittent alernator failure on '93 ATX?


> 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
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