engine AUDI A8 1995 D2 / 1.G ATQ Engine Ignition System Checking User Guide

28-20
Component location Overview of Component
Locations, page Page 24
-5

Note:
The engine speed (RPM) sensor detects RPM
and reference marks. The engine cannot be
started without a signal from the engine speed
(RPM) sensor -G28-. If the engine speed (RPM)
sensor -G28- signal fails while the engine is
running, the engine will stop immediately.

Test sequence

- Before performing test, check sensor for proper
installation and proper fitting.

- Disconnect harness connector for the engine
speed (RPM) sensor (identification: gray
harness connector).

Note:
Resistance value of the engine speed (RPM) sensor is based on a
temperature of 20 C. Resistance increases as temperature increases. - Connect multimeter between terminal 2 and 3 for resistance
measurement.

Specification: 730 to 1000
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If specified value is not obtained:

- Replace engine speed (RPM) sensor.
If specified value is obtained:

If specified value is not obtained:
If specified value is obtained: - Connect multimeter to terminals 2 and 1 (shielding) and to terminals 3
and 1 (shielding) for resistance measurement.

Specification: each (no continuity)
- Replace engine speed (RPM) sensor.
- Connect VAG1598/31 test box at wiring harness to ECM, do not
connect ECM Page 24
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If no malfunctions are found in wires: - 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 (shielding) 108
2 (Ground -GND-) 90
3 (signal) 82
- Repair open circuit or short circuit if necessary.
- Replace Engine Control Module (ECM) Page 24
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Engine Coolant Temperature (ECT) sensor
-G62-, checking

Special Tools and Equipment

VAG1526A
VAG1594A
VAG1598/31
VAS5051 with VAG5051/1
- or
VAG1551 with VAG1551/3B
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28-24
Component location Overview of Component
Locations, page Page 24
-5

Test requirement:

Engine cold

Test sequence

- 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 Measurin
g Value Block
Q
Input display group number XXX

When indicated on display:
- Press buttons -0-, -0- and -4- to select "display group number 004" and
press -Q- button to confirm input.
Read Measuring Value Block 4
1
2
3
4

Indicated on display:
- Check indication in display field 3.
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Display fields

1 2 3 4
Display group 004: Coolant temperature, engine at idle
Display xxxx/min xx.xxx V
xxx.x C
xxx.x C
Indicated Engine speed
(RPM) Battery voltage
Coolant temperature Intake Air Temperature (IAT)
Functional
range 630 to 6800 RPM 10.000 to
15.000 V -48.0 to 143.0 C
-48.0 to 143.0 C
Specified
value xxxx/min 12.000 to
15.000 V Temperature value must rise
evenly From ambient temperature up to
120 C
If display field 3 does not have a realistic
indication:

Note:
Intake air hose between Mass Air Flow (MAF)
sensor and intake air elbow must be removed in
order to be able to reach the coolant temperature
sensor.

- Disconnect connector at coolant temperature
sensor.
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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
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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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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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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
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