AUDI A6 1998 C5 / 2.G AEB Engine Ignition Coil System Checking

28-17


Individual ignition coil system,
checking

Ignition coils, checking


Notes:

Measuring the primary resistance of the ignition
coils is normally not necessary for this test
(primary resistance approx. 0.4 to 0.6 ,
measured between coil terminals 1 and 15).

A high tension isolation diode is installed in the
secondary circuit of the ignition coil. Measuring
the resistance of the secondary coil is therefore
not possible with conventional measuring
instruments.

Required special tools and test equipment
Multimeter US 1119 (Fluke 83 or equivalent)
VW 1594 connector test kit

Test conditions
No fuel injector malfunction stored in DTC
memory
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Checking

- Check DTC memory Page 01
-15
.

There must be no malfunctions stored

- If DTC memory is not clear, make necessary
repairs and erase DTC memory, stop engine
and start engine again, road test, check and
erase DTC memory again.
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28-18

- By briefly disconnecting fuel injector connectors
with engine running, check which cylinder is
misfiring, or not firing at all.

Note:
A misfiring cylinder can also be isolated by
pulling the spark plug connectors (carbon-fouled
plug).

- Check spark plug connector resistance.


Specified value: approx. 2 k If resistance is NOT OK:

- Reconnect spark plug connector.

- Interchange spark plug with one from cylinder
that is OK.

- If other cylinder now misfires, replace faulty
spark plug.

- If same cylinder misfires, interchange ignition
coil with one from cylinder that is OK.

-
If other cylinder now misfires, replace faulty
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coil.

- If original cylinder still misfires, check secondary circuit ground
connection for open circuit between coil connector terminal 4a and
engine Ground.
- If Ground connection is OK, check:

Primary wiring and power supply Page 28
-19

Final output stage for ignition coils Page 28
-21
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28-19

Wiring for primary coil and power
supply, checking


Required special tools and test equipment

VAG 1527B LED voltage tester
VW 1594 connector test kit
Wiring diagrams

Test conditions
Fuse for ignition coils OK

Checking

- Disconnect 4-pin harness connector from power
output stage.

- Switch ignition on.

Note: - Connect VAG 1527B LED voltage tester in turn between 4-pin
connector terminals 1, 2, 3 and 4, and engine ground.
LED must light up for all 4 terminals
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The power supply for the primary circuit is measured via the fuse and
primary coil of the ignition coil.
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28-20
If the LED in the tester does not light up:

- Check wiring for open circuits between power output stage and
terminal 1 at each coil connector, according to table.

Specified value: max. 1.5

If the wiring is OK: - Ignition coil connector terminal identification
Black 4-pin connector terminal
number (power output stage) Ignition coil terminal 1 at
connector for cylinder number:
1 1
2 2
3 3
4 4
- Check wiring for open circuit between each coil terminal 15 and fuse
and power supply, according to wiring diagram.

Specified value: max. 1.5
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28-21

Power output stage for ignition coils,
checking


Required special tools and test equipment

VAG 1598/22 test box
Multimeter US 1119 (Fluke 83 or equivalent)
VAG 1527B LED voltage tester
VW 1594 connector test kit
Wiring diagrams

Note:
To check power output stage, disconnect all
connectors for fuel injectors and then erase DTC
memory.
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28-22

Checking signal for power output stage

- Disconnect 5-pin harness connector from power
output stage.

If the LED in the tester does not blink: - Connect VAG 1527B LED voltage tester in turn between 5-pin
connector terminals 1, 2, 4 and 5, and engine ground.
- Crank starter for a few seconds in each case.
LED must blink all 4 times
- Connect VAG 1598/22 test box to ECM harness connector Page 01
-
56
.

- Check wiring for open circuit between ECM/test box and 5-pin harness
connector, according to wiring diagram.

Connector terminal 1 to ECM/test box socket 70
Connector terminal 2 to ECM/test box socket 78
Connector terminal 4 to ECM/test box socket 77
Connector terminal 5 to ECM/test box socket 71
Specified value: max. 1.5
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28-23
If the wiring is OK:

If the wiring is OK, but the LED in the tester did not blink: - Check for open circuit between 5-pin connector terminal 3 and engine
Ground.

Specified value: max. 1.5 - Replace Motronic ECM -J220- Page 01
-57
.
- Carry out adaptation of throttle valve control module to ECM Page
24
-119
.
- Check readiness code Page 01
-59
. If Diagnostic Trouble Code
(DTC) memory has been erased, or ECM was disconnected, generate
new readiness code Page 01
-62
.
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