check AUDI A6 1998 C5 / 2.G AHA Engine Motronic Ignition System User Guide

28-12

Continuation

- Disconnect 3-pin connector from Knock Sensor
(KS) 1 -G61-.

If resistance is OK (no continuity): - Connect multimeter US1119 (Fluke 83 or equivalent) to measure
resistance between connector terminals, using adapters from VW1594
connector test kit.

Connector terminals 1 and 2
Connector terminals 1 and 3
Connector terminals 2 and 3
Specified value:
- Connect VAG1598/22 test box to Motronic ECM harness connector
page 01
-67
.

- Check wiring for open circuit between ECM/test box and 3-pin harness
connector, according to wiring diagram.

Connector terminal 1 to ECM/test box socket 68
Connector terminal 2 to ECM/test box socket 67
Connector terminal 3 to ECM/test box socket 67
Specified value: max. 1.5
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28-13


If the wiring is OK:
If the malfunction still exists (stored in DTC memory): - Check wiring for short circuits between terminals of 3-pin connector,
and between connector and ECM/test box.

Connector terminal 2 to ECM/test box socket 68
Connector terminal 3 to ECM/test box socket 68
Specified value:
- Loosen knock sensor and tighten to 20 Nm (15 ft lb).
- Replace Knock Sensor (KS) 1 -G61-.
- Check readiness code page 01
-70
.
If Diagnostic Trouble Code (DTC) memory has been erased, or ECM
has been disconnected, generate new readiness code page 01
-73
.
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28-14

- Disconnect 3-pin connector from Knock Sensor
(KS) 2 -G66-.

If resistance is OK (no continuity): - Connect multimeter US1119 (Fluke 83 or equivalent) to measure
resistance between connector terminals, using adapters from VW1594
connector test kit.

Connector terminals 1 and 2
Connector terminals 1 and 3
Connector terminals 2 and 3
Specified value:
- Connect VAG1598/22 test box to Motronic ECM harness connector
page 01
-67
.

- Check wiring for open circuit between ECM/test box and 3-pin harness
connector, according to wiring diagram.

Connector terminal 1 to ECM/test box socket 60
Connector terminal 2 to ECM/test box socket 67
Connector terminal 3 to ECM/test box socket 67
Specified value: max. 1.5
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28-15


If the wiring is OK:
If the malfunction still exists (stored in DTC memory): - Check wiring for short circuits between terminals of 3-pin connector,
and between connector and ECM/test box.

Connector terminal 2 to ECM/test box socket 60
Connector terminal 3 to ECM/test box socket 60
Specified value:
- Loosen knock sensor and tighten to 20 Nm (15 ft lb).
- Replace Knock Sensor (KS) 2 -G66-.
- Check readiness code page 01
-70
.
If Diagnostic Trouble Code (DTC) memory has been erased, or ECM
has been disconnected, generate new readiness code page 01
-73
.
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28-16

Misfire recognition, checking


Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable

Checking

- Connect VAG1551/1552 Scan Tool (ST) and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) page 01
-8 .
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -8- to select "Read Measuring Value Block"
function 08, and press -Q- button to confirm input.
Read Measuring Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -1- and -4- to input display group number 14 (014),
and press -Q- button to confirm input.
Read Measuring Value Block 14 1 2 3 4

Indicated on display (1-4 display groups)
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-
Press button.
- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.

- Check readiness code page 01
-70
.

If Diagnostic Trouble Code (DTC) memory has
been erased, or ECM has been disconnected,
generate new readiness code page 01
-73
.
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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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28-22

Checking

- Check DTC memory page 01
-16
.

There must be no malfunctions stored

- If DTC memory is not clear (malfunctions
recognized):

- Make necessary repairs and erase DTC
memory.

- Stop engine and start engine again.

- Road test.

- Check and erase DTC memory again.

- By briefly disconnecting fuel injector connectors
with engine running, check which cylinder is
misfiring, or not firing at all.
A misfiring cylinder can also be isolated by
examining the spark plugs (for a carbon-fouled
plug).

-
Interchange spark plug with one from cylinder
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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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