AUDI A4 1999 B5 / 1.G AWM Engine Motronic Injection System Servicing Repair Manual

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If specified value is not obtained:

- Replace central electronics.

Checking activation of Fuel Pump (FP) relay

- Switch ignition off.

- Connect VAG1598/31 test box at wiring harness
to Engine Control Module (ECM), do not connect
ECM Page 24
-19
.

- Switch ignition on.

- Bridge terminals 1 and 65 at test box using wires
from VAG1594A adapter test kit.

If relay triggers now, but didn't during output DTM:
If relay does not trigger:
Fuel Pump (FP) relay (at position 4 of central electronics in driver's
footwell, left) must trigger.
- Replace Engine Control Module (ECM) Page 24
-22
- Switch ignition off.
- Remove cable bridge.
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- Remove Fuel Pump (FP) relay.
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If specified value is not obtained:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
If specified value is obtained: - Connect multimeter for voltage measurement as follows.Central electronicsin driver-side footwell, left,
position 4
Terminal
Measure to
19 Engine Ground
(GND)
- Switch ignition on.

Specification: approx. battery voltage
- Check wire connections.
- Check the following wire connection for open circuit and short circuit to
Ground (GND) and B+: Central electronicsin driver-side footwell, left,
position 4
Terminal
VAG1598/31 test
box


Socket
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16 65
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- Repair open circuit or short circuit if
necessary.
If no malfunctions are detected:

- Replace Fuel Pump (FP) relay -J17-.

- Re-connect Engine Control Module (ECM).

Check voltage supply for Fuel Pump (FP) and
components

- Remove fuses S228, S232, and S234 (positions 28, 32, and 34) from
fuse holder.
- Initiate output Diagnostic Test Mode (DTM) Page 01
-51
and activate
Evaporative Emission (EVAP) canister purge regulator valve -N80-.
- Connect multimeter for voltage measurement to Ground (GND) and to
one terminal of the following fuses in the fuse holder. Circlip
Specified value at one of the terminals
S228 approx. battery voltage
S232 approx. battery voltage
S234 approx. battery voltage
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If specified values are not obtained:

- Repeat test at another terminal of fuse socket.
If specified values are not obtained again:

- Check wire connections.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations If no malfunctions are detected:

- Replace Fuel Pump (FP) relay -J17-.

- Re-insert the fuses.
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Mass Air Flow (MAF) sensor -G70-,
checking

Special Tools and Equipment

VAG1526A
VAG1594A
VAG1598/31
VAS5051 with VAG5051/1
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Component location Overview of component
locations Page 24
-5

Test requirements:

Coolant Temperature at least 80 C.

Electrical consumers switched off (radiator
fan must NOT run during test).
A/C switched off.

Checking function

- Connect VAS5051 tester Page 01
-7 and
select vehicle system "01 - Engine electronics".
Engine must run at idle for this.

Display on VAS5051:
- In selection -1-, click on the diagnostic function "04 - Basic setting".
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Display on VAS5051:
1 - Enter display group Max. input value = 255
- Select function "002" in button field -2- for "display group number 002"
and press Q button to confirm input.

Display on VAS5051:
- Check specified values for load detection in display fields -3- and -4-.
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Display fields

1 2 3 4
Display group 002: Air mass taken in with engine at idle and operating temperature
Display xxx /min xxx %
xx.x ms
xxx.x g/s
Indicated Engine speed (RPM) Load
mean injection time
Air mass
Specified value FWD: 740 to 860 RPM
AWD: 820 to 880 RPM 15 to 35 %
1.0 to 4.0 ms
2.0 to 4.5 g/s
Note --- ---
If specified value is not obtained: Evaluation Page 24
-63

If specified value is obtained:

-
End function "04 - Basic setting" by pressing
button.
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