oil AUDI A4 1998 B5 / 1.G AHA Engine Motronic Ignition System Workshop Manual

28-20
Evaluation of display groups 15 and 16 Display groups: 15
and 16


Display fields: 2 and
3
Possible malfunction cause
Corrective action
greater than 5

Ignition coil faulty
Spark plug connector faulty
Spark plug faulty
Power output stage for
ignition coil faulty - Check ignition coils -N-, -N128- and -N158- with power output
stage -N122 page 28
-21



Fuel injector faulty
Not enough fuel- Check fuel injectors page 24
-102
- Check fuel in tank
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28-21

Ignition coils and power output stage,
checking


Notes:

The ignition coils and power output stage are
one component.
Measuring the primary resistance of the ignition
coils is not possible.
Measure secondary resistance first with ignition
wires connected to the ignition coil via the spark
plug connector of the respective cylinder (with
this method the interference resistances of the
ignition cables are also measured).
Component locations page 24
-1

Required special tools and test equipment

Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit

Test conditions
No fuel injector malfunction stored in DTC
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that is OK.
If a different cylinder now misfires:

- Replace faulty spark plug.
If the original cylinder misfires:

- Check ignition coil page 28
-23
.
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28-23

Checking ignition coils -N-, -N128- and -N158-


- Disconnect 5-pin connector from ignition coil
assembly.

- Remove ignition wires from spark plugs.

If resistance is NOT OK: - Using multimeter and adapters from VAG1594 connector test kit,
measure resistance between both spark plug connectors of respective
ignition circuit (across coil).

Specification: approx. 18-25 k .- Remove ignition wires from ignition coils and measure resistance
between ends of respective ignition wires.

Specification: approx. 4.0-6.0 k
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28-24


If resistance values are not as specified:
If resistance values are OK: - Using multimeter and adapters from VAG1594 connector test kit,
measure resistance across both ignition wire connectors of respective
ignition coil.

Specification: 8.0-14.0 k - Replace coils.
- Check signal for power output stage page 28
-25
.
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28-25

Checking signal for power output stage

- Remove connectors from all 6 injectors (DTC
memory will have to be checked and erased
later).

- Switch ignition on.

If LED flashes: - Connect LED tester VAG1527 between engine ground and connector
terminal 3.
- Crank starter for several seconds.
LED in voltage tester must flash.
- Repeat test on 5-pin connector terminals 4 and 5.
- Replace ignition coils -N-, -N128- and -N158- with power output stage -
N122-.
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28-27

Checking ground for power output stage

- Disconnect 5-pin connector from ignition coils.

If LED does not light up:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
binder - Connect VAG1527 LED voltage tester between B+ and terminal 2
(ground) of connector.
LED in tester must light up.
- Check wires for open circuit per wiring diagram.
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28-28

Checking voltage supply of ignition coils

Test requirement

Fuse for ignition coils OK

- Disconnect 5-pin connector from ignition coils.

- Switch ignition on.

If LED does not light up:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
binder - Connect VAG1527 LED voltage tester between engine ground and
terminal 1 (B+) of connector.
LED in tester must light up.
- Check wires for open circuit per wiring diagram.
- Check fuse for ignition coils.
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