AUDI A4 1997 B5 / 1.G AEB ATW Engines Charge Air System With Turbocharger Owner's Manual

21-62

- Initiate output Diagnostic Test Mode (DTM) and
activate the wastegate bypass regulator valve -
N75-.

Repair Manual, 1.8 Liter 4-Cyl. 5V Turbo Fuel
Injection & Ignition, Repair Group 01 Output Diagnostic Test Mode Waste
gate B
ypass Re
gulator Valve -N75

Indicated on display
If valve does not click:
If valve does not open and close properly:
Checking internal resistance Valve must click...
...and must open and close (can be tested by blowing into assisting
hose).
- Check internal resistance of valve.
- Replace wastegate bypass regulator valve -N75-.
- Disconnect harness connector at valve.

- Connect multimeter at valve for resistance measurement.

Specified value: 25-35
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21-63
If specified value is not obtained:

- Replace wastegate bypass regulator valve -N75-
.
If the specified value is met:

Checking voltage supply

If LED does not light:
Electrical Wiring Diagrams, Troubleshooting & Component Locations - Connect VAG1527B voltage tester as follows:Harness connector
terminal
Measure to
1 Engine Ground (GND)
- Operate starter briefly.

LED must light.
- Check wire connection from terminal 1 to Fuel Pump (FP) relay via
fuse for open circuit:
- Repair open circuit if necessary.
Pa
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ystem with turbochar
ger
(en
gine code ATW
)
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21-64
If wire connection is OK:

- Check Fuel Pump (FP) relay:

Repair Manual, 1.8 Liter 4-Cyl. 5V Turbo Fuel
Injection & Ignition, Repair Group 24 If LED lights:

Checking activation

Repair Manual, 1.8 Liter 4-Cyl. 5V Turbo Fuel Injection & Ignition,
Repair Group 01
If LED does not blink or if it remains constantly lit:
Repair Manual, 1.8 Liter 4-Cyl. 5V Turbo Fuel Injection & Ignition,
Repair Group 24 - Connect VAG1527B voltage tester to harness connector terminals 1
(B+) and 2.
- Initiate output Diagnostic Test Mode (DTM) and activate the wastegate
bypass regulator valve -N75-.
LED must blink.
- Connect VAG1598/31 test box at wiring harness to ECM, do not
connect ECM:
Pa
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ystem with turbochar
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gine code ATW
)
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21-65


If wire connection is OK:
Repair Manual, 1.8 Liter 4-Cyl. 5V Turbo Fuel Injection & Ignition,
Repair Group 24 - Check the following wire connection for open circuit and short circuit to
Ground (GND) and B+: Harness connector
terminal
VAG1598/31 test box
socket
2 104
- Repair open circuit or short circuit if necessary.
- Replace Engine Control Module (ECM):
Pa
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(en
gine code ATW
)
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21-66


Charge air pressure sensor -G31-,
checking

Special tools and equipment

VAG1526A
VAG1594A
VAG1598/31
VAS5051 with VAG5051/1
- or
VAG1551 with VAG1551/3A
Pa
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ystem with turbochar
ger
(en
gine code ATW
)
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21-67

Note:
The charge air pressure sensor -G31- and wire
connections are monitored by the Engine Control
Module (ECM).

- Connect VAS5051 tester or VAG1551 scan tool
and select control module for engine electronics
using "address word 01". Engine must run at idle
for this:

Repair Manual, 1.8 Liter 4-Cyl. 5V Turbo Fuel
Injection & Ignition, Repair Group 01
- Check DTC memory of Engine Control Module
(ECM):

Repair Manual, 1.8 Liter 4-Cyl. 5V Turbo Fuel
Injection & Ignition, Repair Group 01 If a malfunction relating to the charge air
pressure sensor -G31- is indicated:

Checking voltage supply

- Disconnect harness connector at charge air
pressure sensor.
Pa
ge 26 of 42 Char
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ystem with turbochar
ger
(en
gine code ATW
)
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- Connect multimeter between terminals 1 and 3 of harness connector
for voltage measurement.
Pa
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21-68

- Switch ignition on.


Specified value: approx. 5 V
If specified value is not obtained:

Repair Manual, 1.8 Liter 4-Cyl. 5V Turbo Fuel Injection & Ignition,
Repair Group 24 - Connect VAG1598/31 test box to wiring harness -2- for Engine Control
Module (ECM), also connect ECM -1-. Connect Ground (GND) clamp -
3- to negative battery post.

If the specified value is met: - Check the following wire connections for open circuit and short circuit
to Ground (GND) and B+: Harness connector
terminal
VAG1598/31 test box
socket
1 108
3 98
- Repair open circuit or short circuit if necessary.
Pa
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ystem with turbochar
ger
(en
gine code ATW
)
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21-69

Checking signal wire

- Connect harness connector at charge air
pressure sensor.

- Connect multimeter to socket 101 and socket
108 of test box for voltage measurement.

- Start engine and run at idle.


Specified value: approx. 1.90 V

- Bring up engine RPM by suddenly depressing
pedal.

Specified value: 2.00-3.00 V
If specified values are not obtained:

- Check the following wire connection for open circuit and short circuit to
Ground (GND) and B+: Harness connector
terminal
VAG1598/31 test box
socket
4 101
- Repair open circuit or short circuit if necessary.
Pa
ge 29 of 42 Char
ge air s
ystem with turbochar
ger
(en
gine code ATW
)
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p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
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pair&id=AUDI.B5.GE02.21.3

If wire connection is OK:
- Replace charge air pressure sensor -G31-.
Pa
ge 30 of 42 Char
ge air s
ystem with turbochar
ger
(en
gine code ATW
)
11/18/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE02.21.3