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

24-3


5 -
EVAP canister purge regulator valve -N80-
6 -
Power output stage -N122-
5-pin connector: signal wiring from ECM4-pin connector: coil primary circuit
connections
7 -
Mass Air Flow (MAF) sensor -G70- In upper air cleaner housing
8 -
Wastegate bypass regulator valve -N75-
9 -
Ignition coils Cylinder 1: -N-Cylinder 2: -N128-Cylinder 3: -N158-Cylinder 4: -N163-
10 -
Fuel injectors Cylinder 1: -N30-Cylinder 2: -N31-Cylinder 3: -N32-Cylinder 4: -N33-
Pa
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24-5

Safety precautions


WARNING!

Fire hazard! Do not smoke, work near heaters
or open flame, or have anything nearby that
could ignite fuel. The fuel system is under
pressure. Before opening, cover connections
with a rag, and open carefully to release
pressure. Be alert when working on or near
the engine and ignition wires. High secondary
ignition voltage can cause serious personal
injury and damage vehicle components.

DO NOT touch or disconnect ignition system
wires when the engine is running or being
cranked at starting RPM.
DO NOT operate starter if fuel injectors are
removed.

Be sure the ignition is switched OFF, when:
Disconnecting or connecting the battery,
ignition wires, or test equipment leads
Disconnecting fuel injection system wiring
Washing the engine or engine
compartment.
Pa
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24-17

Heated Oxygen Sensor (HO2S) and
oxygen sensor control (before TWC),
checking


Notes:

Connector for Heated Oxygen Sensor (HO2S)
before Three Way Catalytic Converter (TWC):
4-pin, brown
Component location Page 24
-1

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

Test conditions

Pa
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port Fuel In
jection
(MFI
) and i
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11/19/2002 htt
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24-23
Evaluation of display group 33 Display group:
33


Display field: 2
Possible cause
Corrective action
approx. 0.435
V
Open circuit in wiring between HO2S connector terminal 4 and
ECM - Check reference voltage Page
24
-24
.
approx. 0.435
V
Open circuit in wiring between HO2S connector terminal 3 and
ECM
approx. 1.085
V Short circuit to positive (B+) between HO2S connector terminal
4 and ECM - Check HO2S wiring Page 24
-
25
.
approx. 0.000
V
Short circuit to Ground between HO2S connector terminal 4
and ECM
Pa
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jection
(MFI
) and i
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11/19/2002 htt
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pair&id=AUDI.B5.FU02.24.1

24-24

Checking HO2S reference voltage

- Disconnect 4-pin connector -1- (brown) for
HO2S -G39-.

If voltage is NOT OK:
If voltage is OK: - Connect multimeter US 1119 (Fluke 83 or equivalent) between harness
connector terminals 3 and 4 (to ECM), using adapter cables from VW
1594 connector test kit.
- Start engine and measure voltage.
Specified value: 0.40-0.50 volts
- Switch ignition off.
- Check HO2S wiring Page 24
-25
- Replace Heated Oxygen Sensor (HO2S) -G39-.
Pa
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(MFI
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11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.1

24-25

Checking HO2S wiring

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

- Disconnect 4-pin connector (brown) for HO2S -
G39-.

- Check wiring for open circuit between ECM/test box and 4-pin HO2S
harness connector (to ECM).

Connector terminal 3 to ECM/test box socket 25
Connector terminal 4 to ECM/test box socket 26
Specified value: max. 1.5
- Check wiring for short circuits between terminals of 4-pin connector,
and between connector and ECM/test box.

Connector terminal 4 to ECM/test box socket 25
Specified value:
- Check wiring for short circuits to wiring harness shielding.

Connector terminal 3 to ECM/test box socket 2
Connector terminal 4 to ECM/test box socket 2
Specified value:
Pa
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port Fuel In
jection
(MFI
) and i
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11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
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pair&id=AUDI.B5.FU02.24.1

24-26
If wiring is OK:

- 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
.
Pa
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port Fuel In
jection
(MFI
) and i
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11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.1

24-27

Oxygen Sensor (O2S) heater (before
TWC), checking


Notes:

Harness connector for Oxygen Sensor (O2S)
heater: 4-pin, brown
Component locations Page 24
-1 .

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

Test requirements
Fuse for Oxygen Sensor (O2S) heater OK
Pa
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jection
(MFI
) and i
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11/19/2002 htt
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24-32
If there is no voltage:

If there is still no voltage: - Connect multimeter between harness connector terminal 1 (to ECM)
and vehicle Ground, using VW 1594 connector test kit.
Specified value: 11.0-14.5 volts
- Check wiring between terminal 1 and relay panel using appropriate
wiring diagram.
Pa
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port Fuel In
jection
(MFI
) and i
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11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.1

24-34
If there is no voltage:

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

If wiring is OK: - Check wiring for open circuit between ECM/test box and 4-pin HO2S
harness connector (to ECM).

Connector terminal 2 to ECM/test box socket 27
Specified value: max. 1.5
- Replace Motronic ECM -J220- Page 01
-57
- Initiate 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
.
Pa
ge 47 of 135 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.1