wiring AUDI A4 1996 B5 / 1.G AWM Engine Motronic Injection System Servicing Workshop Manual

24-19

Wire and component testing using
VAG1598/31 test box


Notes:

VAG1598/31 test box is designed so that it can
be simultaneously connected to the wiring
harness at the Engine Control Module (ECM)
and also to the ECM itself.
This is advantageous because electronic
engine control remains fully functional (e.g.
measurement of signals with engine running)
when the test box is attached.
Relevant test procedures note whether Engine
Control Module (ECM) should also be
connected to the test box or not.
Always use VAG1594A connector test kit to
attach measurement devices (e.g. VAG1527B
voltage tester, VAG1526 multimeter etc.).

WARNING!

To avoid damaging electronic components,
set measuring range before connecting test
leads and observe all test requirements.
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24-20

Special Tools and Equipment

Procedure
VAG1598/31
- Switch ignition off.
- Remove Engine Control Module (ECM) Page 24
-22
.

After re-connecting the Engine Control Module (ECM), the following
work steps must be performed: - Connect VAG1598/31 test box to connector of wiring harness. Connect
Ground (GND) clip at test box (not visible in illustration) 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.
- Activate Engine Control Module (ECM) in "Guided Troubleshooting"
below diagnostic object "Engine Control Module (ECM), replacing".
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24-39

Checking voltage supply

Test requirements:

Fuse for fuel injectors OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

Fuel Pump (FP) relay OK; checking Page 24
-52
.

- 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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Electrical Wiring Diagrams, Troubleshooting & Component Locations - Check wire connection between terminal 1 and fuse for injector valves
for open circuit:
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24-41
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 the 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
-22
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24-45

Fuel injectors, removing and installing


- Remove engine cover (arrows).
- Disconnect wiring/connectors at:
- Fuel injectors -N30-, -N31-, -N32-, -N33-
- Intake Air Temperature (IAT) sensor -G42-
- Camshaft Position (CMP) sensor 2 -G40-
- Throttle valve control module -J338-

- Remove retaining bolts for fuel supply rail and disconnect vacuum line
at fuel pressure regulator (arrows).
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24-49

Test requirement:

Fuel pressure OK, checking Page 24
-32
.

Test sequence

- Remove fuel distributor including fuel injectors
from intake manifold Page 24
-45
. Fuel lines
remain connected.

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

Checking Proper Seal

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

- Switch ignition on.


Fuel Pump (FP) must run.

- Check proper seal of fuel injectors (visual
inspection). With Fuel Pump (FP) running, only 1
to 2 drops per minute may drip out per injector.

-
If fuel loss is greater, stop Fuel Pump (FP) from
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24-55
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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24-56


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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24-58
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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