AUDI A4 1998 B5 / 1.G ATW Engine Ignition System Owner's Guide

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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 VAG1551/3A
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Component location Overview of component
locations Page 24
-5

Test requirement:

Engine cold

Test sequence

- Connect VAS5051 tester or VAG1551 scan tool
and select control module for engine electronics
using "address word" 01 Page 01
-10
. Engine
must run at idle.
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
Enter displa
y 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.x volts
xxx.x C
xxx.x C
Indicated Engine speed
(RPM) Battery
voltage Coolant temperature Intake Air Temperature (IAT)
Functional
range
-48.0 to 143.0 C

Specified value xxxx/min 12.0 to 15.0
V Temperature value must rise
evenly From ambient temperature up to
110 C
If display field 3 does not have a realistic
indication:

- Disconnect connector at coolant temperature
sensor.

Coolant temperature sensor with square
connector:

- Connect multimeter between terminal 1 and 3 of sensor for resistance
measurement.
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Coolant temperature sensor with oval
connector:

All models:
Range A shows the resistance values for the temperature range from 0-
50 C, and range B shows the values for the temperature range from 50-
100 C. - Connect multimeter between terminal C and D of sensor for resistance
measurement.

Read-out examples:
If specified value is not obtained:
30 C corresponds to a resistance of 1500 to 2000 80 C corresponds to a resistance of 275 to 375
- Replace coolant temperature sensor.
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If specified value is obtained:

- Connect VAG1598/31 test box at wiring harness
to Engine Control Module (ECM), do not connect
ECM Page 24
-19
.

Coolant temperature sensor with square
connector:

Coolant temperature sensor with oval connector: - Check 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 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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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
-23

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Voltage supply for control module,
checking

Special tools and equipment

VAG1526A
VAG1594A
VAG1598/31
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Test requirements:

Fuses for engine electronics OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

Battery voltage at least 12.7 V
Generator OK

Test sequence

- Connect VAG1598/31 test box at wiring harness
to Engine Control Module (ECM), do not connect
ECM Page 24
-19
.

- Switch ignition on.

Note:

The plus voltage supply for the Engine Control
Module (ECM) travels via terminal 3 and 121
(terminal 15) as well as terminal 62 (terminal
30).

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Ground (GND) supply of the Engine Control
Module (ECM) travels via connector terminal 1
and terminal 2.
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- 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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