diagram AUDI A8 1999 D2 / 1.G AEB Engine Motronic MFI And Ignition System

24-67


- Check wiring resistance for open circuit between ECM/test box and 4-
pin ECT sensor connector.

Connector terminal 1 to ECM/test box socket 53
Connector terminal 3 to ECM/test box socket 67
Specified value: max. 1.5

- Check wiring for short circuit between ECM/test box and 4-pin harness
connector according to wiring diagram.

Connector terminal 1 to vehicle Ground
Connector terminal 1 to ECM/test box socket 67
Connector terminal 1 to terminal 3
Connector terminal 3 to vehicle Ground
Specified value:
- Check wiring between ECM and 4-pin harness connector for short
circuit to battery B+. Specified value: 0 volts

Connector terminal 1 to vehicle Ground
Connector terminal 3 to vehicle Ground
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24-69

Intake Air Temperature (IAT) sensor,
checking


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 diagram
Chilling spray (commercially available)
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24-73

- Check wiring for short circuit between ECM/test
box and 2-pin harness connector according to
wiring diagram.


Connector terminal 1 to vehicle Ground

Connector terminal 1 to ECM/test box
socket 67

Connector terminal 1 to terminal 2

Connector terminal 2 to vehicle Ground

Specified value:

- Check wiring between ECM and 2-pin harness
connector for short circuit to battery B+.


Connector terminal 1 to vehicle Ground

Connector terminal 2 to vehicle Ground

Specified value: 0 volts

- Check resistance across terminals of IAT sensor -G42-.
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24-75

Engine Speed (RPM) sensor, checking


Required special tools and test equipment

VAG 1598/22 test box
Multimeter US 1119 (Fluke 83 or equivalent)
VW 1594 connector test kit
Wiring diagram

Checking

- Disconnect 3-pin harness connector from engine
speed sensor Page 24
-1 , Component
locations

- 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.

Connector terminal 1 to ECM/test box socket 56
Connector terminal 2 to ECM/test box socket 63
Connector terminal 3 to ECM/test box socket 2
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24-76

- Check wiring for short circuit between ECM/test
box and 4-pin harness connector, according to
wiring diagram.


Connector terminal 1 to ECM/test box
socket 2

Connector terminal 1 to ECM/test box
socket 63

Connector terminal 2 to ECM/test box
socket 56

Specified value:
If wiring is OK:

- Replace engine speed (RPM) sensor -G28-.

- 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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24-77

Voltage supply to Engine Control
Module (ECM)


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 diagram

Checking

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

Indicated on display
- Press buttons -0- and -8- to select "Read Measuring Value Block"
function 08, and press -Q- button to confirm input.
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24-80
If voltage is NOT OK:

- Check wiring according to applicable wiring
diagram.

Checking voltage supply at terminal 15

- Switch ignition off.

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

- Connect multimeter between ECM/test box
sockets 1 (B+) and 2 (Ground), using adapter
cables from VW 1594 connector test kit.

- Switch ignition on, and check voltage.

Specified value: 10-14.5 volts
If voltage is NOT OK:

- Check wiring according to applicable wiring
diagram.

-
Check readiness code Page 01
-59
. If
Diagnostic Trouble Code (DTC) memory has
been erased, or ECM was disconnected,
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24-82
If the fuel pump does not respond:

- Check power supply wiring Page 24
-84
.
If the LED test light does not light up:

- Repeat test at other terminal of fuse 28.

If the LED light still does not light up:
- Check wiring for open or short circuits between fuse 28 and terminal 30
at relay position 6, using the applicable wiring diagram. Repair wiring
as necessary.

Note:
This step lets the fuel pump run without the engine running. The closed
throttle position switch must be closed during the test, or the selected fuel
injector will discharge fuel when it is actuated 5 times. - Connect VAG 1527B LED voltage tester between Ground and one of
the two terminals for fuse 29.
-
Initiate output Diagnostic Test Mode (DTM) and advance to test of
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24-83
If the LED test light does not light up:

- Repeat test at other terminal of fuse 29.

If the LED test light does not light up:
- Check wiring for open circuit between fuse 29 and terminal 30 at relay
position 6, using the applicable wiring diagram. Repair wiring as
necessary.

Note:
This step lets the fuel pump run without the engine running. The closed
throttle position switch must be closed during the test, or the selected fuel
injector will discharge fuel when it is actuated 5 times. - Connect VAG1527 LED voltage tester between Ground and one of the
two terminals of fuse 34.
- Initiate output Diagnostic Test Mode (DTM) and advance to test of
cylinder 1 fuel injector -N30- Page 01
-42
.

LED test light must light up
Fuel pump relay must be activated
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24-84
If the LED test light does not light up:

- Repeat test at other terminal of fuse 34.

If the LED test light does not light up:
Checking fuel pump relay voltage supply
If voltage is NOT OK: - Check wiring for open circuit between fuse 34 and terminal 31 at relay
position 6, using the applicable wiring diagram. Repair wiring as
necessary.
- Remove fuel pump relay -J17- from relay panel position 6.
- Switch ignition on.
- Connect multimeter US 1119 (Fluke 83 or similar) and check for
voltage at relay socket:

Terminals 28 (B+) and 34
Terminals 32 (B+) and 34
Specified values: approx. Battery Positive Voltage (B+)
- Repair wiring according to applicable wiring diagram.
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