On 9/5/2009 9:35 PM Steve Williams wrote:

> This morning in Grants, NM, when I started the engine, the alternator
> and oxygen sensor lights were on until I revved the engine
> slightly.  Then both lights went out.
>
> It hasn't done that before, and it worried me,

It would worry me if the ALT lamp didn't behave like that. Until the
engine is revved a bit the lamp stays lit. It's meant to light up if the
alternator isn't putting out enough voltage. When the van is first started
and at idle, the alternator doesn't output enough voltage for the
regulator to start doing anything useful. But with a bit of a rev the
alternator boots, the regulator gets it under control, and the ALT lamp
goes dark.

The same event is often used in Vanagons with aux batteries to drive the
relay that connects the aux battery to the starter battery so the aux
battery can get charging current if it needs it. In Mellow Yellow I can
feel the Stancor relay in the aux battery box under the driver's seat pull
in with a "clack" sound when that lamp goes dark.

--
Mike "Rocket J Squirrel" Elliott
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
Bend, OR
KG6RCR