diagram AUDI A4 1999 B5 / 1.G AEB Engine Turbocharger Boost Control And Checking

24-129

Check voltage supply for wastegate bypass
regulator valve -N75-

Note:
Voltage supply for the wastegate bypass
regulator valve is provided by the fuel pump
relay.

Fuse for -N75- OK

- Disconnect harness connector from valve.

If LED does not light:
If wiring is OK: - Connect VAG 1527B LED test light between harness connector
terminal 1 and engine Ground.
- Operate starter motor.
LED test light must light up
- Check wiring for open circuit between terminal 1 to and fuse, according
to wiring diagram. Repair if necessary.
- Check fuel pump relay Page 24
-81
.
Pa
ge 8 of 17 Turbochar
ger boost controls, checkin
g
11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.3

24-131

Barometric Pressure (BARO) sensor,
checking


Note:
The signal from Barometric Pressure (BARO)
sensor -F96- influences:

Boost pressure limit
Mixture composition at engine start-up

Required special tools and test equipment
VAG 1551 or VAG 1552 Scan Tool (ST) with
VAG 1551/3 adapter cable
VAG 1598/22 test box
Multimeter US 1119 (Fluke 83 or equivalent)
VW 1594 connector test kit
Wiring diagrams

Checking

Pa
ge 10 of 17 Turbochar
ger boost controls, checkin
g
11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.3

24-134

Checking wiring

- Disconnect harness connector from Barometric
Pressure (BARO) sensor.

- Switch ignition on.

If voltage is NOT OK: - Connect multimeter US 1119 (Fluke 83 or equivalent) and check
voltage between connector terminals 1 and 3 (Ground) as well as 2
and 3 (Ground), using adapter cables from VW 1594 connector test kit.
Specified value for both: 4.5-5.5 volts
- Switch ignition off.
- Connect VAG 1598/22 test box to ECM harness connector Page 01
-
56
.

- Check wiring for open circuit between ECM/test box and 3-pin harness
connector, according to wiring diagram.

Connector terminal 1 to ECM/test box socket 61
Connector terminal 2 to ECM/test box socket 62
Connector terminal 3 to ECM/test box socket 67
Specified value: max. 1.5
Pa
ge 15 of 17 Turbochar
ger boost controls, checkin
g
11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.3