1995 AUDI A6 AEB Engine Turbocharger Boost Control And Checking

24-130

Signal for wastegate bypass regulator valve,
checking

- Disconnect harness connector for valve -N75 .

If LED test light does not blink, or stays on continuously: - Connect VAG 1527B LED voltage tester between connector terminals
1 (B+) and 2.
- Start output Diagnostic Test Mode (DTM) and advance through test
program to select wastegate bypass regulator valve -N75- Page 01
-
42

LED test light must blink
- Connect VAG 1598/22 test box to ECM harness connector Page 01
-
56
.

If wiring is OK: - Check wiring for open circuit or short circuit to B+ between connector
terminal 2 and ECM/test box socket 64. Repair if necessary.
- Replace Motronic ECM -J220- Page 01
-57
.
- Carry out adaptation of throttle valve control module to ECM Page
24
-119
.
- Check readiness code Page 01
-59
. If Diagnostic Trouble Code
(DTC) memory has been erased, or ECM was disconnected, generate
new readiness code Page 01
-62
.
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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

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- Connect VAG 1551 or VAG 1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) Page 01
-7 .
Rapid data transfer
HELP
Select function XX

Indicated on display
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24-132

- Press buttons -0- and -8- to select "Read
Measuring Value Block" function 08, and press -
Q- button to confirm input. Read Measurin
g Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -1-, -1- and -3- to input display group number 113, and press -Q-
button to confirm input.
Read Measuring Value Block 113 1 2 3 4

Indicated on display (1-4 = display fields)
- Compare displayed value with specified air pressure value (display field 4):

Display fields

1 2 3 4
Display group 113: Boost pressure regulation
Display xxx RPM xx.xx ms
xxx
xxxx mbar
1)

Indicates Engine speed
(in 40 RPM steps) Engine load Throttle valve angle Air pressure
Range 0-6800 RPM 0.00-8.50 ms
0-90
559-1118 mbar
Specified value 0 RPM 0.00 ms
0-5 0 m
400 m
1000 m
1013 mbar
970 mbar
900 mbar
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2000 m
3000 m
800 mbar
700 mbar
1) Pressure fluctuations caused by weather conditions are not considered
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24-133

- Check air pressure with turbocharger tester VAG
1597/A (actual pressure indication) and compare
with displayed value.
If the displayed value is so high or low that it
seems implausible for the altitude or the air
pressure:

- Check wiring and terminals for excessive
resistance Page 24
-134
.
If displayed value is NOT OK:

- Check readiness code Page 01
-59
. If
Diagnostic Trouble Code (DTC) memory has
been erased, or ECM was disconnected,
generate new readiness code Page 01
-62
.

-
Press button to advance program
sequence.
- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.
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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
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24-135

- Check wiring for short circuits between terminals
of 3-pin connector, and between connector and
ECM/test box.


Connector terminal 2 to ECM/test box
socket 61

Connector terminal 3 to ECM/test box
socket 61

Connector terminal 3 to ECM/test box
socket 62

Specified value:
If wiring is OK:

- Replace Barometric Pressure (BARO) sensor.
If an implausible value is still displayed after
replacing the barometric pressure sensor:

- Replace Motronic ECM -J220- Page 01
-57
.

- Carry out adaptation of throttle valve control
module to ECM Page 24
-119
.

-
Check readiness code Page 01
-59
. If
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