1996 AUDI A4 diagram

24-73

Checking voltage supply

If there is no voltage:
Checking wiring - Disconnect 3-pin harness connector from Mass Air Flow sensor (MAF).
- Connect multimeter US1119 (Fluke 83 or equivalent) between harness
connector terminals 2 (Ground) and 3 (B+), using adapter cables from
VW1594 connector test kit.
Specified value: 9.0-14.5 volts
- Switch ignition off.
- Check wiring using applicable wiring diagram.
- Switch ignition off.
- Connect VAG1598/22 test box to ECM harness connector page 01
-
67
.
- Check wiring for open circuits, between ECM/test box and 3-pin MAF
sensor harness connector.

Connector terminal 1 to ECM/test box socket 13
Connector terminal 2 to ECM/test box socket 12
Specified value: max. 1.5
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24-74

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


Connector terminal 1 to ECM/test box
socket 12

Specified value:

- Switch multimeter to 20 VDC measuring
range.

- Check wiring at 3-pin connector for short circuit
to B+ (battery positive voltage), according to
applicable wiring diagram.


Connector terminal 1 to vehicle Ground

Connector terminal 2 to vehicle Ground

Specified value: 0 volts
If wiring is OK:

- Replace Mass Air Flow sensor (MAF) -G70-.

-
Check readiness code page 01
-70
. If
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p://127.0.0.1:8080/audi/servlet/Dis
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24-75

Engine Coolant Temperature (ECT)
sensor, checking


Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit
Wiring diagram

Test requirements
Engine cold
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24-80


- 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+.

Connector terminal 1 to vehicle Ground
Connector terminal 3 to vehicle Ground
Specified value: 0 volts
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p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
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pair&id=AUDI.B5.FU03.24.1

24-82

Intake Air Temperature (IAT) sensor,
checking


Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit
Wiring diagram
Chilling spray (commercially available)
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p://127.0.0.1:8080/audi/servlet/Dis
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24-86


If wiring is OK: - 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
Specified value:
- Check wiring between ECM and 2-pin harness connector for short
circuit to battery B+.
Specified value: 0 volts

If resistance is NOT OK: - Check resistance across terminals of IAT sensor -G42-.

Specified value at approx. 20 C (68 F): approx. 1.5-3.5 k- Replace intake air temperature sensor -G42-.
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p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
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24-88

Engine Speed (RPM) sensor, checking


Note:
Component locations page 24
-1

Required special tools and test equipment

VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit
Wiring diagram

Checking

- Disconnect 3-pin harness connector from engine
speed sensor.

- Connect VAG1598/22 test box to ECM harness
connector page 01
-67
.
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24-89


If wiring is OK: - Check wiring for open circuit between ECM/test box and 3-pin harness
connector.

Connector terminal 1 to ECM/test box socket 67
Connector terminal 2 to ECM/test box socket 63
Connector terminal 3 to ECM/test box socket 56
Specified value: max. 1.5
- Check wiring for short circuit between ECM/test box and 3-pin harness
connector, according to wiring diagram.

Connector terminal 2 to ECM/test box socket 67
Connector terminal 1 to ECM/test box socket 63
Connector terminal 1 to ECM/test box socket 56
Specified value:
- Replace engine speed (RPM) sensor -G28-.
- Check readiness code page 01
-70
. If Diagnostic Trouble Code
(DTC) memory has been erased, or ECM was disconnected, generate
new readiness code page 01
-73
.
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11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1