RE: VAG scan tool & codes for V8

["Buchholz, Steven" <Steven.Buchholz@kla-tencor.com>]

> And finally, does anybody have a list of fault codes for a 1991 V8Q? I
> am getting codes 3433, 3434, 3443, 3444 and can not find them listed
> anywhere.

... I think I figured out what was going on ... by any chance was the dash
alarm bell chiming during the 3444 code?  The sequence of numbers that you
saw are the codes that are displayed when you run the instrument cluster
output diagnostics!  I did not see them listed in my paper copy, but on the
fiche they were there ... and there were some pretty cool diagnostics.  As
most V8 owners know, the radiator's electric auxiliary fan is controlled by
the instrument cluster.  One of the output diagnostics runs the rad fan
through all three of its speeds, another sets temp and pressure gauges to
specific levels for testing.  When I get a chance I'll try to write more
down (kinda tough to transcribe from the fiche while standing up in the
garage ...).

I couldn't find anything that was specific to the Rapid Transfer format for
the VAG1551 as you requested, but I did make some notes about the four
connectors on the V8.  The leftmost connector (black?) is actually only to
provide +12 and ground.  12 volts is on the upper pin and ground on the
lower.  The next connector (blue?) is the one that provides the path for the
rapid transfer format, and the bottom pin on the connector is used to
activate the flash codes much like the old 5k's fuse in the fuel pump relay.
A jumper from the ground pin on the bottom of the leftmost connector to the
bottom pin on the adjacent connector for 4 seconds activates the ECU flash
codes.  If your car doesn't have a check engine light you can connect a low
wattage lamp from the top pin on the leftmost connector (12V) to the top pin
on the rightmost connector.  The third connector is used to read codes from
the instrument cluster.  You can hook a test lamp from the 12V pin on the
leftmost connector to the bottom pin on the third connector from the left to
read the IC codes.  Grounding the pin on the third connector activates the
diagnostic sequence.  Automatic transmission codes are read out through the
PRNDL display, but I didn't look into the method for activating them.  

Finally, contrary to my statement from yesterday, I found that even on the
V8 the 1551 provides the ability to do more than simply read out the error
codes.  There are 10 blocks of information which include sensor values and
ECU parameters that the VAG1551 can read in rapid transfer mode.  

HTH!
Steve Buchholz
San Jose, CA (USA)