1996 AUDI A4 AEB ATW Engines Charge Air System With Turbocharger Workshop Manual

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
ge 25 of 42 Char
ge air s
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
ge air s
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
ge 27 of 42 Char
ge air s
ystem with turbochar
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(en
gine code ATW
)
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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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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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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
)
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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
)
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The shop air supply line will later be attached to the inlet of VAG 1687. - Close valve -3- before gauge.
- Close valve -4- after gauge.
- Remove female fitting from tester (arrow) and install an appropriate
"male" air fitting that will connect to your shop air supply line (
WARNING!).
Pa
ge 32 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