check engine AUDI A6 1999 C5 / 2.G ATQ Engine Motronic On Board Diagnostic Workshop Manual

01-3

Malfunction Indicator Lamp (MIL),
significance

If the ECM recognizes malfunctions that lead to a
degradation of emissions values, it indicates
them by lighting the Malfunction Indicator Lamp
for exhaust.

Installation position of exhaust MIL
Note:
The Malfunction Indicator Lamp (MIL) can blink or remain lit continuously.
DTC memory should be checked in both cases Page 01
-15
.
Blinking: There is a malfunction that causes damage to the catalytic
converter in this driving condition (e.g. combustion misfire). In this
case, vehicle must only be driven at reduced power! Continuously lit: There is a malfunction that causes increased
emissions. Check DTC memory for Motronic ECM and automatic
transmission (if installed). If there are driveability problems or if there is a customer complaint
and the exhaust MIL is not lit, DTC memory must be checked. There
may be DTCs stored that do not cause the exhaust MIL to light up
immediately, but only if malfunction is recognized again after repeated
engine starts.
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01-6

- Check the following wire connection for open
circuit and short circuit to B+:

Test box
VAG1598/31
Socket
Instrument cluster

Terminal
47 Electrical Wiring Diagrams,
Troubleshooting & Component
Locations binder

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

- Replace Engine Control Module (ECM) Page
24
-21
.
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01-7

B - Warning lamp for On Board Diagnostic
(Malfunction Indicator Lamp -MIL-) remains lit
constantly

- Check DTC memory of Engine Control Module
(ECM) Page 01
-15
.
If no DTCs are stored:

- Connect VAG1598/31 test box at wiring harness
to ECM, do not connect ECM Page 24
-17
.

- Remove instrument cluster:

Repair Manual, Electrical Equipment, Repair
Group 90, Instrument cluster, removing and installing


- Check the following wire connection for short
circuit to Ground (GND):

Test box
VAG1598/31
Socket
Instrument cluster

Terminal
47 Electrical Wiring Diagrams,
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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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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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01-14
Selectable functions VAS 5051 vehicle diagnostic, testing and information
system or VAG1551 Scan Tool (ST) Ignition
on,
engine
off Engine running
at idle Vehicle in drive
mode page
Address words
01 Engine electronics Yes Yes Yes Page
01
-9
00 Automatic test sequence Yes Yes Yes Page
01
-11

Functions
01 Check Control Module Versions Yes Yes Yes Page
01
-13

02 Check DTC Memory No Yes Yes Page
01
-15

03 Output Diagnostic Test Mode (DTM) Yes No No Page
01
-56

04 Basic Setting Yes Yes Yes Page
01
-66

05 Erase DTC Memory Yes Yes Yes Page
01
-15

06 End Output Yes Yes Yes Page
01
-17

07 Code Control Module Yes No No Page
01
-71

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