> 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