fuses AUDI A4 1996 B5 / 1.G AEB Engine Motronic MFI And Ignition System

BEFORE cranking engine at starting RPM
(e.g. for compression testing) disable ignition
and fuel injection systems:

Disconnect both ignition coil power output
stages, and both Motronic fuses at the E-box
in the plenum.
Disconnect harness connectors from all fuel
injectors.
Afterward, erase DTC memory.
Pa
ge 6 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

24-81

Fuel pump relay and connections,
checking


The fuel pump relay is located at relay position 4 on the relay panel on the
left side under the instrument panel.
Checking function of fuel pump relay -J17-
- Remove storage shelf in left-front footwell.

- Remove fuses 28, 29 and 34 from fuse panel.
- Connect VAG 1527B LED voltage tester between Ground and one of
the two terminals for fuse 28.
- Briefly crank starter.

LED test light must light up.
Fuel pump relay must be actuated (sound and vibration)
Pa
ge 110 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

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