Steve Eiche seiche at shadetreesoftware.com
Thu May 8 20:38:33 EDT 2003

Yes, you can run diagnostic and check for stored codes without using a
scan tool.  It is really quite simple.  If you car has a check engine
light, there is no need to use an LED.  If your car does not have the
light, the socket should be there so all you have to do is plug a bulb
in.  If you cannot find the socket behind the dash (behind the three
small gauges on the right), you can use an LED and jumper as shown on
Scott Mockry's web site (http://www.sjmautotechnik.com/ecuf20v.html) or
the Bentley manual.  If you have the light, you only need a jumper wire.
  As long as you don't short the two wires on the black plug (12V and
ground), you really can't hurt anything.

Basically, to run the tests, put a jumper from the L line (brown
connector, connection away from the clip) to ground (black connector,
connetion away from the clip or any ground) for 5 seconds.  This
initiates the blink code fault display on the check engine light if the
engine is running, or the output tests if it is not.  If you do not have
a check engine light, you can connect an LED test light between the
connection on the blue plug (the only wire there, connection close to
the clip) and 12V (black plug, connection closest to clip or any 12V

Having a scan tool like our ProDiag is nice, especially on the newer
cars with more complete diagnostics or if you need to track down a tough
problem with requires you to monitor measuring blocks, but you can
easily make do with just the jumper on a 3B.


Steve Eiche
Shade Tree Software, LLC

I never received an answer regarding being able to run
diagnostics/checking for stored codes on the 200 20V tq with 3B
engine.  I referenced Audi service manual/Bentley as well as SJM site
and the information seems ambigous or incomplete.  I wanted to check
for stored codes without using a ROSS/VAG-COM or VAG 1551 or equivalent.

I was just trying to make up a rudimentary harness to run diags using
the connectors under the dash.  There are 3 connectors Black,
LightBrown, and BLUE.  SJM site says BLue connector not used, but
picture shows three connectors.

Section D2-20-1 in Bently shows Dark connector red wire(+) --LED--
resistor---Br/G wire(from control unit) and switched wire returning to
the Br wire(-).  I see this as possibly a short circuit between + and -
   Is that what is supposed to happen - and only 2 wires are used?

Is this the same way to initiate diags on the 3B as well? I don't want
to blow anything out.

Any other helpful tips/BTDT on gathering information on the state of
the systems would be most helpful.  This may be rhetorical, but I would
like to get an analyzer - what is available for not much $$$?


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