1997 AUDI A4 APB Engine Ignition System Checking

28-8
If malfunction remains at the same cylinder.

- Disconnect harness connector from ignition
coil.

Electrical Wiring Diagrams, Troubleshooting & Component Locations
If the Ground (GND) connection is OK. - Check Ground (GND) connection between socket 4a and engine
Ground (GND) for open circuit and short circuit to B+. - Repair any open/short circuit as necessary.
- Connect hand-held multimeter (voltage range) to terminal 15 of
harness connector and Ground (GND).
- Disconnect harness connector from fuel injector of cylinder to be
tested.
- Operate starter.
Specified value: approx. battery voltage
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28-9
If the specification is not obtained:

- Check wiring.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations If the specification is obtained:

- Disconnect 3-pin harness connectors on power
output stages for ignition coils; component
locations overview Page 24
-5 .

- Then connect diode test lamp to 3-pin
connectors for both output stages.

If the specifications are not obtained: - Connect diode test lamp VAG1527 to following contacts on connectors
for power output stages: 3-pin harness connector
terminal
Specification
(with starter activated)
1 + Ground (GND) Diode test lamp should
2 + Ground (GND) light up
3 + Ground (GND)
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- Switch ignition off.
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28-10


Check the following wiring connections for open circuits and/or short to B+
or Ground (GND).
Black 3-pin connector on power
output stage, terminal
3-pin connector on ignition
coil, terminal
1 1 (cylinder 1)
2 1 (cylinder 2)
3 1 (cylinder 3)
Brown 3-pin connector on power
output stage, terminal
3-pin connector on ignition
coil, terminal
1 1 (cylinder 4)
2 1 (cylinder 5)
3 1 (cylinder 6)
- Eliminate any open/short circuit as necessary.
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28-11

Power output stages for ignition coils,
checking


Note:

Power Output Stage -N122 (black connector)
activates the ignition coils for cylinder bank 1
(cylinders 1 to 3).
Power Output Stage 2 -N192 (brown connector)
activates the ignition coils for cylinder bank 2
(cylinders 4 to 6).

Checking activation of power output stages

- Disconnect harness connectors from all six fuel
injectors.

Note:
It is important to ensure that no fuel is injected
during the test as this would damage the catalytic
converter. The harness connectors on the fuel
injectors must therefore be disconnected.
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28-12

- Disconnect 4-pin harness connectors on power
output stages Component locations overview,
Page 24
-5 .

- Connect diode test lamp VAG1527 in turn to the following contacts on
the two 4-pin connectors for the power output stages.
- Then, operate starter for a few seconds.
6-pin connector on wiring harness,
terminal
Specification
1 + Ground (GND) Diode test lamp
should
3 + Ground (GND) flash (brief impulse)
4 + Ground (GND)
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28-13
If the specifications are not obtained:

- Switch ignition off.

- Connect test box VAG 1598/31 to wiring
harness for engine control module. Do not
connect to the engine control module itself.
Page 24
-20
.

The following wiring connections are to be checked for open circuits
and/or short to B+ or Ground (GND).
Black 4-pin connector on wiring
harness, terminal VAG1598/31 test box,
socket
1 94
3 110
4 102 Brown 4-pin connector on wiring
harness, terminal VAG1598/31 test box,
socket
1 95
3 111
4 103
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28-14

- Rectify any open/short circuit as necessary.
If no wiring malfunction is detected:

- Connect 4-pin connectors to power output
stages.

- Disconnect 3-pin connectors from power output
stages.

- Connect diode test lamp VAG1527 to battery
(B+) and to one of the 3 terminals on power
output stage.

- Operate starter for few seconds.

The diode test lamp should flash.

- Carry out test with all 3 terminals on each of the
3-pin connectors for the power output stages.

The diode test lamp should flash each time.
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