ground AUDI A3 1998 8L / 1.G ATW Engine Motronic Fuel Injection Syst

24-20

Special tools and equipment

Procedure
VAG1598/31
- Switch ignition off.
- Remove Engine Control Module (ECM) Page 24
-23
.

- Connect VAG1598/31 test box to connector of wiring harness. Ground
(GND) clip at test box (not visible in illustration) must be connected to
Ground (GND). Relevant test procedures note whether Engine Control
Module (ECM) should also be connected to the test box.
- Perform test as described in relevant repair sequence.
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Checking voltage supply

Test requirements:

Fuse for fuel injectors OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

Fuel Pump (FP) relay OK; checking Page 24
-53
.

- Disconnect harness connector at the fuel
injector to be tested.

If LED does not light up: - Connect VAG1527B voltage tester as follows:Harness connector
Terminal
Measure to
1 Engine Ground (GND)
- Switch ignition on.

LED must light up.
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If LED does not blink:

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

If wire connection is OK: - Check following wire connections for open circuit and short circuit to
Ground (GND) and B+: Cylinder
Fuel injector harness connector
Terminal
VAG1598/31 test box
Socket
1 2 96
2 2 89
3 2 97
4 2 88
- Repair open circuit or short circuit if necessary.
- Replace Engine Control Module (ECM) Page 24
-23
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Checking Injection Quantity

- Insert fuel injector to be tested in a measuring
glass from VAG1602 injection quantity test
device.

- Connect one terminal of fuel injector to engine Ground (GND) using an
adapter cable and an alligator clip from VAG1594A connector test kit.
- Connect second terminal of fuel injector to B+ using VAG1348/3A
remote control, VAG1348/3-2 adapter cable and assisting cable.
- Bridge terminals 1 and 65 at test box using wires from VAG1594A
adapter test kit.
- Bridge terminals 1 and 65 at test box using wires from VAG1594A
adapter test kit.
- Switch ignition on.

Fuel Pump (FP) must run.
- Activate VAG1348/3A remote control for 30 seconds.
- Perform measurement on all fuel injectors.
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Component location Overview of component
locations Page 24
-5 .
Voltage is supplied to the Fuel Pump (FP) and
several components of the injection system via
the Fuel Pump (FP) relay -J17-.
Engine must be turning for Fuel Pump (FP) relay
-J17- to close. This means that the relay does
not receive Ground (GND) (via ECM) until the
ECM recognizes RPM signals.

Test requirement:

Battery voltage at least 12.7 V

Function test of Fuel Pump (FP) relay

- Remove driver-side storage compartment.

Repair Manual, Body Interior, Repair Group
68


- Connect VAS5051 tester or VAG1551 scan tool
and select control module for engine electronics
using "address word" 01 Page 01
-10
. Ignition
must remain switched on.

-
Initiate output Diagnostic Test Mode (DTM)
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A - If relay does not trigger:
B - If relay triggers, but Fuel Pump (FP) does not run:
Check voltage supply of Fuel Pump (FP) relay
Fuel Pump (FP) relay (at position 4 of central electrics in driver's
footwell, left) must trigger and Fuel Pump (FP) must run.
- Check voltage supply of Fuel Pump (FP) relay Page 24
-55
.
- Checking activation of Fuel Pump (FP) relay Page 24
-56
.
- Check voltage supply for Fuel Pump (FP) and components (via Fuel
Pump -FP- relay) Page 24
-58
.
- Remove Fuel Pump (FP) relay.

- Connect multimeter to terminal 17 of relay socket and Ground (GND)
for voltage measurement.

Specification: approx. battery voltage
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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 electronics in driver-side footwell, left,
position 4
Terminal
Measure to
19 Engine Ground
(GND)
- Switch ignition on.

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


Socket
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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
-49
and activate
Evaporative Emission (EVAP) canister purge regulator valve -N80-.
- Connect multimeter for voltage measurement to Ground (GND) and to
one terminal of following fuses in 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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Voltage supply for Mass Air Flow (MAF)
sensor, checking

Test requirements:

Fuse for Mass Air Flow (MAF) sensor OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

Fuel Pump (FP) relay OK; checking Page 24
-53
.

Note:
Voltage is supplied to Mass Air Flow (MAF)
sensor from Fuel Pump (FP) relay.

- Disconnect connector from Mass Air Flow (MAF)
sensor.

- Connect multimeter for voltage measurement as follows.Harness connector
Terminal
Measure to
2 Engine Ground (GND)
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If specified value is not obtained:

- Check wire connection from terminal 2 of
connector to Fuel Pump (FP) relay via fuse for
open circuit and short circuit to Ground (GND):

Electrical Wiring Diagrams, Troubleshooting &
Component Locations
- Repair open circuit or short circuit if
necessary.

Note:
Ground (GND) from the ECM is present at terminal 3 of connector.
If specified value is not obtained: - Connect multimeter to terminal 2 and terminal 3 of connector for
voltage measurement.
- Operate starter briefly (engine can also start).

Specification: approx. battery voltage
- Check wire connections Page 24
-67
.
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