fuel AUDI A6 1997 C5 / 2.G AEB ATW Engines Charge Air System With Turbocharger User Guide

21-61

Note:
The wastegate bypass regulator valve -N75- 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 wastegate bypass
regulator valve -N75- is indicated:

- Disconnect hoses from valve; harness connector
remains connected.

-
Attach assisting hose to one connection of
Pa
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ystem with turbochar
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gine code ATW
)
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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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ge 21 of 42 Char
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ystem with turbochar
ger
(en
gine code ATW
)
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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
ge 22 of 42 Char
ge air s
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
ge 23 of 42 Char
ge air s
ystem with turbochar
ger
(en
gine code ATW
)
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play?action=Goto&t
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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
ge 24 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
yp
e=re
pair&id=AUDI.B5.GE02.21.3

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
ge air s
ystem with turbochar
ger
(en
gine code ATW
)
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p://127.0.0.1:8080/audi/servlet/Dis
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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
ge 28 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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21-70

Charge pressure leak test with VAG
1687


Intake system, checking for leaks using VAG
1687 Diagnostic Tool
Diagnostic trouble codes (DTCs) related to fuel
trim, charge pressure or mass air flow (MAF)
may be caused by:

Leaking (worn/torn) intake hoses during charge
conditions
Incorrectly torqued or improperly placed clamps
on intake hoses etc. causing leaks during
charge conditions

Check the charge air pressure system using the VAG 1687 Charge air
system tester.
Special tool VAG 1687 Charge air system tester preliminary set-up

- Back off pressure regulator knob -2- of VAG 1687 fully to protect gauge
when shop air supply is applied to assembly.
Pa
ge 31 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