Date: Sat, 23 Jun 2001 20:47:45 -0700
Reply-To: Mark Drillock <drillock@EARTHLINK.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mark Drillock <drillock@EARTHLINK.NET>
Subject: Re: Digifant circuits
Content-Type: text/plain; charset=us-ascii
Neither of these wires are grounds. Look at Bentley page 97.123 for more
info on ECU pin 20. Pin 23 seems to be a way for the ECU to know that
the Digifant Control Unit Relay is supposed to be enabled. This may be a
way for a fault code system to detect a failure of this relay. I am not
aware of such a fault code system in our Vanagons but other cars have it
and it became mandatory at some point. OBD was the first type required
AFAIK. The diagram on 97.123 shows pin 20 connected to an indicator
light called ECS-MAL, or ECS Malfunction I would guess. There is also a
switch on this circuit but it may be there only to test the light. I
have never owned a Vanagon newer than 87 so I have no had a chance to
explore this stuff.
Mark
Joel Walker wrote:
>
> > I've been meaning to post this for a while. I have an '86 and a '91
> Vanagon-both
> > Digifant controlled. The '91 uses two additional circuits; pins 20 &
> 23 that
> > are not used on the '86. What does the '91 Digifant need to know
> that the '86
> > does not??? These two circuits are shown in the Bentley.
>
> my guess is that 20 and 23 are extra ground wires.
>
> in the Vanagon Fuel Injection diagnosis book (published in 1987),
> neither pin 20 nor pin 23 show up in the circuit diagram for Digifant.
>
> but in the generalized Digifant I/Digifant II diagnosis book
> (published in 1988), pin 23 DOES show up ... as a ground wire from pin
> 23 on the ECU to pin 85 on the power supply relay (the one that does
> NOT power the fuel pump; in the black box over the ignition coil, in
> the engine compartment).
>
> now, look at the Bentley diagram for 1990 and later, pin 20 on the ECU
> (page 97.205in Bentley) seems to go to "single connector, under
> instrument panel, left side" (T1o, see page 97.203 for description of
> that terminal connector) ... and that's where all the ground wires
> cluster. it doesn't SAY it's a ground wire, and it's the wrong color
> for a ground wire. but i don't know what else it would be.
>
> so maybe vw figured out about all the bad grounds in their design?? :)
>
> joel
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