1999 AUDI A8 ATQ Engine Motronic On Board Diagnostic Workshop Manual

Troubleshooting & Component
Locations binder

- Repair short circuit if necessary.
If wire connection is OK:

- Replace Engine Control Module (ECM) Page
24
-21
.
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01-8

Safety precautions

If special testing equipment is required during
road test, note the following:

WARNING!

Scan tools and testing devices must always
be secured on the rear seat and operated
from there by a second person.
If a scan tool or testing device were to be
operated from the passenger seat and there
were an accident involving activation of the
passenger-side airbag, the person seated
there could be seriously injured.
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01-9

VAS 5051 vehicle diagnostic, testing
and information system orVAG1551
Scan Tool (ST), connecting and
selecting functions


Test requirements:

Fuses for engine electronics OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder

Fuel Pump (FP) OK, checking Page 24
-
49
.

Battery voltage at least 12.7 V
Ground (GND) connections at engine and
transmission OK

Procedure

Note: - Connect VAS5051 tester to vehicle with VAS5051/1 diagnostic wire.
Alternately, VAG1551 Scan Tool (ST) can also be attached using
VAG1551/3B cable.
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Data Link Connector (DLC) is located in front left knee bolster.
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01-10

WARNING!

Observe safety precautions Page 01
-8 .

Note:
The following description only explains
implementation of On Board Diagnostic using
VAG1551 Scan tool.
When using the VAS5051 tester, observe the
tester's instructions for use V.A.G - ON BOARD DIAGNOSTIC
HELP
1 - Rapid data transfer 1)2 - Blink code output 1
)

Indicated on display: 1) Operating modes 1 and 2 are displayed alternately
Note:
If nothing appears in display:
- Perform troubleshooting procedure after "troubleshooting procedure leak
test":
Electrical Wiring Diagrams, Troubleshooting & Component Locations
binder
Depending on desired function Table "Selectable functions", page
Page 01
-14
:
- Switch ignition on.
or
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- Start engine.
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01-11

- Press -Print- button to turn on Scan Tool (ST)
printer. Indicator lamp in button must light up.

- Press button 1 to select "Rapid data transfer"
operating mode 1. Rapid data transfer
HELP
Insert address word XX

When indicated on display:
Note:
The address word 00 initiates the automatic test sequence, i.e. it results in
a DTC check on all OBD capable systems in the vehicle via rapid data
transfer.
- Press buttons -0- and -1- to select "engine electronics" and press -Q-
button to confirm input.
3B0907551BA
2.8l V6/5V
G
0003
Codin
g 07251
WSC 12345

VAG1551 Scan Tool (ST) display indicates control module identification,
e.g.:
Note:
Control module identification can be printed by pressing the PRINT key of
the VAG1551 scan tool.
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01-12

Control module identification (example)

3B0907551
BA part number; allocation
Parts Catalog 2.8 LEngine displacement V6/5VConstruction style of engine (V
engine, 6 cylinder, 5 valves) "G" i.e. no
indication Vehicle with or without cruise
control system 0003Data version (software
version) of control module Coding
07251 Control module coding WSC 12345 Factory identification of
VAG1551, with which the last
coding was performed

-
Press button.
Rapid data transfer
HELP
Select function XX

Indicated on display (function selection):
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