1999 AUDI A8 wiring

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
ge 45 of 135 Motronic Multi
port Fuel In
jection
(MFI
) and i
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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

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

24-35

Oxygen Sensor (O2S) behind Three Way
Catalytic Converter (TWC) and oxygen
sensor control, checking


Notes:

Harness connector for Oxygen Sensor (O2S)
behind Three Way Catalytic Converter (TWC):
4-pin, black
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

Pa
ge 48 of 135 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
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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

24-39
Evaluation of display group 36 Display group:
36


Display field: 1
Possible causes
Corrective action
approx. 0.435
V
Open circuit in wiring -4- between oxygen sensor and ECM - Check basic voltage Page 24
-40
approx. 0.440
V
Open circuit in wiring -4- between oxygen sensor and ECM
approx. 1.085
V Short circuit to B+ in wiring -4- between oxygen sensor
and ECM - Check wiring for oxygen sensor
Page 24
-41

approx. 0.000
V
Short circuit to Ground in wiring -4- between oxygen
sensor and ECM
Pa
ge 53 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

24-40

Checking HO2S reference voltage

- Disconnect 4-pin connector (black) for Oxygen
Sensor (O2S) behind Three Way Catalytic
Converter (TWC) -G108-.

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 to 0.50 volts
- Switch ignition off.
- Check HO2S wiring Page 24
-41
- Replace HO2S behind TWC -G108-.
Pa
ge 54 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

24-41

Checking HO2S wiring

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

- Disconnect 4-pin connector (black) for Heated
Oxygen Sensor (HO2S) behind Three Way
Catalytic Converter (TWC) -G108-.

- 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 51
Connector terminal 4 to ECM/test box socket 52
Specified value: max. 1.5
- Check wiring for short circuits between terminals of 4-pin connector,
between connector, ECM/test box, and shielding for wiring harness.

Connector terminal 4 to ECM/test box socket 51
Connector terminal 3 to ECM/test box socket 2
Connector terminal 4 to ECM/test box socket 2
Specified value:
Pa
ge 55 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

24-42
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
ge 56 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

24-43

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


Notes:

Harness connector for Oxygen Sensor (O2S)
heater: 4-pin, black
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
ge 57 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