Date:         Tue, 13 Jul 1999 22:34:30 -0400
Reply-To:     Martin Jagersand <jag@CS.YALE.EDU>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Martin Jagersand <jag@CS.YALE.EDU>
Subject:      Annoying charging system problem
Comments: To: diesel@vwfans.com

The Westy stopped charging the battery some days ago. Alt light
on all the time.

Changed voltage regulator. No go.
Changed alternator. Also no go.
Checked for shorts or other problems. None found.

Got annoyed for a few days, but this morning I looked at
it again.

The light output on the alt drives at least one relay on the
Westy. This is (annoyingly) not shown in the Bentley wiring diagram.
Relay coil resistance is 70 ohms. Measuring the "ohms"
of the alt light output (for whatever its worth, it's most
likely not a resistive circuit) 3.5 kOhms.

Found out that if I disconnect the alt light circuit the alt
charges as it should. Also if I put 12V to the circuit for a short
while when the engine is running everything pops into normal working
condition.

Cycled the circuit forcibly this way about ten times and now
it seems to work by itself again. I wonder for how long.

Best I can figure is that the alt light output has only marginal
current to drive both the light and the relay. And this seemed true
of both the Bosch alts I tried. Afterwards tried a Motorola and it
seemed to have less internal resistance.

Anyone else had similar problems or symptoms?

/Martin
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