light AUDI A6 2000 C5 / 2.G AEB Engine Motronic MFI And Ignition System

24-19

- Check oxygen sensor control learning values
(display fields 1 and 2):

Display fields

1 2 3 4
Display group 32: Oxygen sensor control learning values
Display xx.x % xx.x %
Indicates Oxygen sensor control learning value at idle
(additive)
(before TWC) Oxygen sensor control learning value at partial load
(multiplicative)
(before TWC)
Range -26.0 to 26.0 % -25.0 to 25.0 %
Specified
value -8.0 to 8.0 %
(can vary slightly) -8.0 to 8.0 %
(can vary slightly)
If not as specified Page 24
-22
, Evaluation of display group 32

If displayed values are OK (as specified):

- Press -C- button.

- Press buttons -0-, -3- and -3- to input display
group number 33, and press -Q- button to
confirm input. Read Measuring Value Block 33

Indicated on display (1-4 = display fields)
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24-37

- Compare display and specified values (display
fields 1 and 2):

Display fields

1 2 3 4
Display group 36: Heated Oxygen Sensor (HO2S) behind Three Way Catalytic Converter (TWC)
Display x.xxx V B1-S2 ON
B1-S2 OFF
Indicates Voltage supply to HO2S behind TWC HO2S behind TWC
ON/OFF
Range 0.000-1.000 V ---
Specified value 0.000-1.000 V
(can oscillate slightly) B1-S2 ON

If not as specified Page 24
-38
, Continuation

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24-56

- Check engine operating conditions (display field
4):

Display fields

1 2 3 4
Display group 5: Engine electronics-operating conditions
Display xxx RPM xx.xx ms xxx km/h Idle
Part throt
Full throt
1)

Decel
Enrich
Indicates Engine speed
(in 40 RPM steps) Engine load Vehicle speed Operational condition
Range 0-6800 RPM 0.00-8.50 ms --- ---
Specified value 760-960 RPM 0.50-1.50 ms 0 km/h Idle: "Idle"
Throttle slightly open: "Part throt"
Throttle quickly closed: "Decel"
Quick acceleration over 3000 RPM: "Enrich"
1) Possible only while driving
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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)
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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
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cylinder 1 fuel injector -N30- Page 01
-42
.

LED test light must light up
Fuel pump relay must be activated
Fuel pump must run
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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
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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.
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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.
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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.
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