AUDI A6 1995 C5 / 2.G ATQ Engine Ignition System Checking Owner's Guide

28-28

Coolant temperature sensor with square
connector:

Coolant temperature sensor with oval connector: - Check the following wire connections for open circuit and short circuit
to Ground (GND) and B+: Harness connector
Terminal
VAG1598/31 test box
Socket
1 (signal) 93
3 108

- Check the following wire connections for open circuit and short circuit
to Ground (GND) and B+: Harness connector
Terminal
VAG1598/31 test box
Socket
3 108
4 (signal) 93
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28-29

All models

- Check both wires to each other for short
circuit.

- Repair open circuit or short circuit if
necessary.
If no malfunctions are found in wires:

- Replace Engine Control Module (ECM) Page
24
-21
.
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28-30


Voltage supply for control module,
checking

Special Tools and Equipment

VAG1526A
VAG1594A
VAG1598/31
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28-31

Test requirements:

Fuse for Engine Control Module (ECM) OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder

Battery voltage at least 12.7 V
Generator OK

Test sequence

- Connect VAG1598/31 test box at wiring harness
to ECM, do not connect ECM Page 24
-17
.

- Switch ignition on.

Note:

The plus voltage supply for the Engine Control
Module (ECM) travels via connector terminal 3
(terminal 15) and connector terminal 62
(terminal 30).
Ground (GND) supply of the Engine Control
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Module (ECM) travels via connector terminal 1
and terminal 2.
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28-32

- Connect multimeter for voltage measurement as
follows:

VAG1598/31 test box
Socket
Measure to
1 B+
2 B+
62 Engine Ground (GND)


Specification: approx. battery voltage

- Connect multimeter for voltage measurement as
follows:

VAG1598/31 test box
Socket
Measure to
3 Engine Ground (GND)

- Switch ignition on.


Specification: approx. battery voltage
If specified values are not obtained:
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- Check wire connections.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder
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28-33

Knock recognition control stop,
checking

The following tests must be performed when a
DTC is stored that relates to "knock recognition
control limit reached".

Possible cause
Corrective action
DTC for all cylinders
Poor fuel quality- Change fuel quality
(see operating instructions)
or
DTC for all cylinders in one
row Knock sensor tightened to incorrect
torque - Loosen knock sensors and tighten to 20
Nm
Knock sensor faulty- Check knock sensors Page 28
-41

Corrosion at harness connector
Engine accessories loose- Secure engine accessories
DTC for one Cylinder Engine damage- Check compression pressure
Engine accessories loose- Secure engine accessories

- Also check ignition angle retardation of the
individual cylinders Page 28
-34
.
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28-34

Check ignition angle retardation of the
individual cylinders

- Connect VAS5051 tester or VAG1551 scan tool
and select the control module for engine
electronics using "address word" 01 Page 01
-
9 .

Engine must run at idle for this.Rapid data transfer
HELP
Select function XX

When indicated on display:
- Press buttons -0- and -8- to select "Read Measuring Value Block" and
press -Q- button to confirm input.
Read Measuring Value Block
Q
Input displa
y group number XXX

When indicated on display:
- Press buttons -0-, -2- and -0- to select "display group number 020" and
press -Q- button to confirm input.
Read Measuring Value Block 20
1
2
3
4

When indicated on display:
- Check indication in all display fields.
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28-35


Display fields

1 2 3 4
Display group 020: Ignition -knock control in driving operation
Display
xx.x KW
xx.x KW
xx.x KW
xx.x KW
Indicated
Ignition angle
retardation cylinder 1
via knock control
Knock sensor control Ignition angle
retardation cylinder 2
via knock control
Knock sensor control Ignition angle
retardation cylinder 3
via knock control
Knock sensor control Ignition angle
retardation cylinder 4
via knock control
Knock sensor control
Specified
value 0 to 12 KW
0 to 12 KW
0 to 12 KW
0 to 12 KW
Notes Evaluation Page 28
-40

Note:
The number values indicated in display fields 1 to 4 represent actual ignition angle retardation via knock control of the
individual cylinders. Ignition angle retardation occurs in KW (crankshaft degrees) toward retardation.
- Press -C- button.Read Measuring Value Block
Q
Input display group number XXX

When indicated on display:
- Press buttons -0-, -2- and -1- to select "display group number 021" and press -
Q- button to confirm input.
Read Measuring Value Block 21
1
2
3
4

When indicated on display:
- Check indication in display field 1 and 2.
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