2000 AUDI A8 ignition

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
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24-89
If LED does not flicker:

- Switch ignition off.

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

- Check wiring for open circuits between ECM/test
box and fuel injector harness connectors:


Cyl. 1 fuel injector terminal 2 to ECM/test
box socket 73

Cyl. 2 fuel injector terminal 2 to ECM/test
box socket 80

Cyl. 3 fuel injector terminal 2 to ECM/test
box socket 58

Cyl. 4 fuel injector terminal 2 to ECM/test
box socket 65

Specified value: max. 1.5

- Check wiring for open circuit between fuel
injector connector terminal 1 and relay panel,
according to wiring diagram.
Pa
ge 121 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

24-92


Note:
When reinstalling the fuel injectors be careful not to damage the O-rings. - Disconnect harness connector for Engine Coolant Temperature (ECT)
sensor -G62-.
-
Adjust VAG 1630 digital potentiometer to 15 k setting.- Connect to ECT sensor harness connector terminals 1 and 3, using
adapter cables from VW 1594 connector test kit.
- With the aid of a helper, briefly crank starter.
Fuel injectors must spray according to the firing order.
- Switch ignition off, and check for leaks at fuel injectors.
Fuel injectors may not drip more than 2 drops per minute.
Pa
ge 126 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

24-95


If residual pressure drops below 2.5 bar (36 psi): - Disconnect vacuum hose (arrow) for fuel pressure regulator.
Fuel pressure must increase to approximately 4.0 bar (58 psi)
- Reconnect vacuum hose.
- Switch ignition off.
- Check for residual fuel pressure by monitoring decrease in pressure on
gauge. Specified value:
After 10 minutes: at least 2.5 bar (36 psi)
- Start engine and let run at idle.
- After pressure has built up, at the same time:
- Switch ignition off.
- Close valve on pressure tester VAG 1318-lever in OFF position
(arrow).
- Monitor decrease in pressure on gauge.
Pa
ge 130 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