RE: Dead 5kTQ Diagnostic quiz

[Porsray@aol.com]

hill@wrksys.enet.dec.com (Paul Hill 223-2154)
Date: Wed, 17 Jul 1996 13:37:24 -0400
Subject: Dead 5kTQ Diagnostic quiz

Partial message:
 
This morning I checked channel 11 again and it read 10.2 volts and there is
no
oil warning symbol, so I tried the starter.  Fired right up but ran rough
with 
low tick over speed.  If I held the throttle to get 2000 rpm it smoothed out.
Now low battery symbol came up on the display.  At no time did the red
ignition
light stay on with the engine running, so I assume the alternator is not 
totally dead.

This seems to be a voltage related issue?  
Either the battery is not being charged, or the battery itself is majorly 
screwed ?

Reply:

Simply because you have no alternator light does not mean the alternator is
good.
>From your description, the alternator is dead.  I had a similar experience
about 3
years back in a 1984 Porsche; was driving back home at dusk and turned on the

headlights.  When it was almost dark, I noticed that the lights awful dim.
 Had
NO alternator warning light.  At about this time, the engine died totally
(computer
probably gave up the ghost due to lack of juice).  The battery fortunately ws
pretty
good; I was able to let it sit for approx. 1/2 hour after which I was able to
start the
car again and drive approx. 10 minutes to a local repair shop.

Diagnosis was a bad alternator; replacement of it cured the problem.  By the
way,
after the car died, I tried switching the ignition "ON" to see if the
alternator light
would come on. Well, it wouldn't!  Might want to check this out.

Battery voltage while running should be about 13.5 volts.

Ray Calvo
porsray@aol.com
1990 Coupe Quattro