[V8] OBD-II Connector

[Buchholz, Steven]

Over winter last year a water leak on 344's front windshield caused
water to pool on the diag connectors, which actually ate through one of
the wires.  I've still not been able to get the car to pass smog, and
without the ability to even blink out the codes I was pretty much stuck.


I gave Chris Semple a call to get replacement connectors ... but I also
asked him if it would be possible to pull an OBD-II connector ... he
said he had an A6 which could probably donate to the cause.  Steve Eiche
suggested I go ahead an install one in place, that way I could directly
connect my ProDiag interface rather than having to work through the
adapter.  I "reverse engineered" the adapter (four wires, big whoop!)
and figured out the wiring in the car.  When I repaired the stock
connector I also splices the OBD-II connector appropriately.  Now I can
still use the adapter ... and blink the codes per the standard procedure
... but I can also plug into the OBD-II connector.  What I've found is
the direct connection seems to allow me to get more consistent logs when
taking a test drive.  

Anyway, here's the pinout I determined for my 1991 V8 5-speed:

OBD-II Pin|Wire color in V8 loom|Pin
  16      | Blu/Blk             | T2a-2 (power)
 4 & 5    | Brn                 | T2a-1 (ground)
  15      | Wht/Blk             | T2i-2
   7      | Blu/Yel             | T2i-1

This will allow your ProDiag (and I'd imagine VAG Com) to hook up to the
Motronic and Tranny ECUs for read and clearing codes and running
diagnostics in the RDT mode.  I don't have the OBD-II connector
permanently mounted to anything, it is sitting in the same cutout as the
factory connectors, just sitting to the right of them.  

Steve B
San Jose, CA (USA)

BTW, the good news was that when I could hook up to the ECU I read codes
that indicated I'm having problems with the heater wires to the OXS ...
I'll bet if I get that fixed I'll finally be able to get the car back on
the roads.  It'd be nice to be able to drive a car to work on a rainy
day (like today) for once!