[T3] Mystery Wires

[Dennis Stiefel]

Some of you guys may not approve how I am putting on this harness but I do
it this way sometimes with FI and engine management systems on modern cars
and it works out ok.  Since we had the FI harness off for the paint job I
decided to install it on the engine before we install the it in the car then
slip the part of the harness that plugs up to the ECU through the hole that
goes in the part where the brain is mounted.  Everything has hooked up ok
but I have 4 mystery wires I'm not sure where they go.  I think one goes to
the temperature sensor in the left head but not sure on that.  The numbers
on these wires are faded out except for one and it has the number 18 on it.
Two of these wires come out behind the generator the other two comes out
close to the wire that goes to the pressure sensor.  I have tried to take
the DVOM and see where they come out on the terminal that plugs into the
ECU.  No reading at all for the two behind the generator and the other two
one has no reading and the one that has 18 on it seems to be tied into the
wire that goes to the thermo switch according to the DVOM.  If I'm not
making any sense I can take either some still photos of this location or do
a you tube video and link it here and try that. We are so close to getting
it in and hearing it run but so far away still it seems. I guess I'm having
a little trouble with this because as some of you all know this FI system
came off a parts car of the same year as this car which has not been running
FI since 1984. This has definitely been like putting to gather a jig saw
puzzle that I didn't see where some of the pieces where to start with. Sorry
for the long post.

 

Dennis Stiefel

72 Fastback         

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OK I think I have most of this figured out now. Just before Russ passed away
he sent me a couple of CD roms with all kind of old manuals and bulletins
from VW and other non VW sources.  I found a diagram that seems to match up
better with what we have than what the Bentley showed.  The two behind the
generator.  One goes to the temperature sensor on the head and the other
goes to one of the other two wires that comes out around the wires that goes
to the pressure sensor so I guess that wires goes where there is a place for
a ground on that sensor and where it comes out behind the generator it needs
to be grounded on the top of the crank case. That leaves me with that last
wire that is tied to the thermo switch wire. From what I have read from
other post here and manuals it is part of the cold start set up and I have
seen more than one person say on here not hook up this part of the system.
If I am wrong than correct me. If I'm right than I guess I just need to tie
this wire up.

Dennis