hi..
of course I've noticed it happens..
and I'm not asking you to explain how the wiring works..
I'm teasingly asking you ..
why did they build it that way !??

I have seen other cars where more than 'THE  warning light will come on' ..
when one important warning is set off.
  And I have seen person in a car with that warning light 'illogic have a
coolant leak and major overheating ..
and since about 3 lights were on, they figured it must be an electrical
glitch ..
so they kept driving until the engine was cooked.
  and *then* ..after replacing the head gasket and attending to any needed
head work..
once running again ..then you could hear a piston knock from damage from
overheating.
  And then everybody was unhappy ..the poor car owner/customer ..the shop
for appearing to not have fixed it properly or completely ( and really ..the
only two choices in a case like that are either do the head job and see how
it is, or tear it all apart to inspect, and then that's a rebuild . )

pretty dumb. That was a Renault LeCar,second generation one, with eletronic
ignition and rectangular headlights - the better ones.   Not many of those
alive anywhere in north america anywhere that I know of anymore  !  ( anyone
want to buy a factory shop manual for one ? )

and all due to silly warning light wiring logic.
so ..WHY .........AGAIN............did VW tie the Alt light OXS light
together electrically ????

and I get that the diode keeps the OXS warning box from turning on the Alt
warning light when it decides to trip the OXS mileage reminder light.  I
really think engineers do not get any training in basic practicality.
 Actually I'd like to start a whole new field..'Practical Sensible
Engineering.'

Overall though ..Vanagons are pretty darn good...they just missed it a
little here and there and we live with it because the vehicles are
inherently and basically so good and well thought out ...mostly.

----- Original Message -----
From: "David Beierl" <dbeierl@attglobal.net>
To: "Scott Daniel - Turbovans" <scottdaniel@turbovans.com>
Cc: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, March 26, 2011 3:35 PM
Subject: Re: Re: Alternator question

> At 06:16 PM 3/26/2011, Scott Daniel  - Turbovans wrote:
>
>>why is the blue wire D + tied into the Oxygen Sensor elasped milage
>>counter box and light ..
>>and why does it say 'cat elapsed milage counter' at the box, track 46,
>>page   97.107  ?
>
> Short answer is that the switch at track 46 (that's the box under the van)
> will light the OXS light when it trips, by grounding its negative lead.
> But *also* the wire at track 45 dives into the fuse/relay panel on plug C,
> comes out on plug A at track 44 where it's referred over to track 50.
> There at the plug B connector it joins the D+ wire heading from the
> instrument panel back to the alternator.  This whole charade is for a bulb
> check - any time D+ is grounded and lights up the ALT light, it will also
> light up the OXS light.  If you haven't noticed that this happens, goes to
> show how good people are at noticing things they see every day (or that
> they drive an '89+ which doesn't have an OXS light).
>
> The diode inside the switchbox at track 45 is so that the OXS switch won't
> attempt to mess with the D+ line when it trips: D+ can pull OXS low, but
> OXS cannot even try to pull D+ low (which it could have trouble doing if
> the alternator were charging, could be some magic smoke let out there
> somewhere as well as a false ALT light.  Which might no longer be false if
> the magic smoke came out).
>
> Yrs,
> d