AUDI A6 1995 C5 / 2.G AEB Engine Motronic MFI And Ignition System

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
Pa
ge 111 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

cylinder 1 fuel injector -N30- Page 01
-42
.

LED test light must light up
Fuel pump relay must be activated
Fuel pump must run
Pa
ge 112 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

24-83
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
Pa
ge 113 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

Fuel pump must run
Pa
ge 114 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

24-84
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.
Pa
ge 115 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

24-85

Checking fuel pump relay signal

Fuel pump relay -J17- removed
Fuses 28, 29 and 34 removed from fuse
panel

If the LED test light does not light up while cranking the starter, check
wiring as follows. - Connect VAG 1527B LED voltage tester between relay socket
terminals 28 (B+) and 29.
LED test light must light up (dimly).
- Briefly crank starter; LED test light must continue to light up (dimly).

If resistance is NOT OK: - Connect VAG 1598/22 test box to ECM harness connector Page 01
-
56
. (Numbers marked on ECM connector match those on test box).
- Connect multimeter US 1119 (Fluke 83 or equivalent) to check for open
circuit between relay socket terminal 29 and test box socket 4.

Specified value: max. 1 - Repair wiring using applicable wiring diagram.
Pa
ge 116 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

Electrical Wiring Diagrams, Troubleshooting & Component Locations.
Pa
ge 117 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

24-86
If the wiring is OK, but the LED test light does not
light up:

- Replace Engine Control Module (ECM) Page
01
-57
.
If the wiring is OK, and the signal to the fuel
pump relay is OK:

- Replace fuel pump relay -J17-.

- Reinstall fuses.
Pa
ge 118 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

24-87

Fuel injector actuation, checking

Triggering fuel injectors via output Diagnostic
Test Mode (DTM) Page 01
-42


Required special tools and test equipment

VAG 1598/22 test box
Multimeter US 1119 (Fluke 83 or equivalent)
VAG 1527B LED voltage tester
VW 1594 connector test kit
Wiring diagram

Test requirements
Fuse for fuel injectors OK
Engine speed (RPM) sensor OK
Fuel pump relay OK
Pa
ge 119 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

24-88

Checking

- Disconnect harness connector from cylinder 1 fuel injector.
- Connect VAG 1527B LED voltage tester between connector terminals
(to ECM), using adapters from VW 1594 connector test kit.
- Disconnect harness connectors from fuel injectors for cylinders 2, 3
and 4.
- Crank starter briefly to check voltage supply for cylinder 1 fuel injector.
LED must flicker.
- Repeat test for fuel injectors for cylinders 2, 3 and 4.
Pa
ge 120 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