engine AUDI A4 1998 B5 / 1.G APB Engine Charge Air System With Turbocharger User Guide

21-21

- Initiate output Diagnostic Test Mode (DTM) and
activate recirculating valve for turbocharger -
N249-.

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel
Injection & Ignition, Engine Code(s): APB, Repair Group 01

Output diagnostic test mode Recr. valve for turbocharger -N249

Indicated on display
If valve does not click:
If valve does not open and close properly: Valve must click...
...and must open and close (can be tested by blowing into assisting
hose).
- Check internal resistance of valve.
- Replace recirculating valve for turbocharger -N249-.
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21-23

Checking voltage supply

Note:
Voltage is supplied to the recirculation valve via
the Fuel Pump (FP) relay.

Test requirement:

Fuse for recirculation valve OK

- Disconnect connector at valve.

- Connect VAG1527B voltage tester as follows:Harness connector terminal
Measure to
1 Engine Ground (GND)
- Operate starter briefly.

LED must light.
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21-24
If LED does not light:

- Check wire connection from terminal 1 to Fuel
Pump (FP) relay via fuse for open circuit.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations
- Repair open circuit if necessary.
If wire connection is OK:

- Check Fuel Pump (FP) relay.

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel
Injection & Ignition, Engine Code(s): APB, Repair Group 24

If LED lights:

- Check activation, Page 21
-25
.
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21-25

Checking activation

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel Injection & Ignition,
Engine Code(s): APB, Repair Group 01

If LED does not blink or if it remains constantly lit:
Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel Injection & Ignition,
Engine Code(s): APB, Repair Group 24
- Connect VAG 1527B voltage tester to connector terminals 1 (B+) and
2.
- Initiate output Diagnostic Test Mode (DTM) and activate recirculating
valve for turbocharger -N249-.

LED must blink.
- Connect VAG 1598/31 test box at wiring harness to ECM. Do not
connect ECM.

- Check the following wire connections for open circuit and short circuit
to Ground (GND) and B+: Harness connector terminal
VAG 1598/31 test box
Bushing
2 9
- Repair open circuit or short circuit if necessary.
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21-26
If wire connection is OK:

- Replace Engine Control Module (ECM).

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel
Injection & Ignition, Engine Code(s): APB, Repair Group 24

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21-28

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

- Connect VAS 5051 tester or VAG 1551 scan
tool and select control module for engine
electronics using "address word" 01. Engine
must run at idle.

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel
Injection & Ignition, Engine Code(s): APB, Repair Group 01


- Check DTC memory of Engine Control Module
(ECM).

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel
Injection & Ignition, Engine Code(s): APB, Repair Group 01

If a Diagnostic Trouble Code (DTC) relating to
the charge air pressure sensor -G31- is
indicated:
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21-29

Checking voltage supply

- Switch ignition off.

- Remove engine cover (arrows).
- Disconnect connector at charge air pressure sensor.

If specified value is not obtained: - Connect multimeter between terminal 1 and 3 of harness connector for
voltage measurement.
- Switch ignition on.

Specification: about 5 V
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21-30

- Connect VAG 1598/31 test box to wiring
harness for Engine Control Module (ECM), also
connect ECM -1-.

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel
Injection & Ignition, Engine Code(s): APB, Repair Group 24


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
VAG 1598/31 or test box
Bushing
1 108
3 98
- Repair open circuit or short circuit if necessary.
- Check signal wire, Page 21
-31
.
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21-31

Checking signal wire

- Disconnect 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.


Specification: about 1.90 V

- Bring engine to RPM by depressing pedal
suddenly.

Specification: approx. 2.00 ... 3.00 V
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