1998 AUDI A3 check engine

24-132

Checking wire connections

If no malfunctions are found in wires: - Pull connector -2- off throttle valve control module.
- Connect VAG1598/31 test box at wiring harness to Engine Control
Module (ECM), do not connect ECM Page 24
-19
.
- Check following wire connections for open circuit and short circuit to
Ground (GND) and B+: Harness connector
Terminal
VAG1598/31 test box
Socket
1 92
2 83
3 117
4 84
5 118
6 91
- Repair open circuit or short circuit if necessary.
- Replace throttle valve control module.
Pa
ge 25 of 51 Electronic En
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(EPC
) (E-Gas
), checkin
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24-134
Both the Throttle Position (TP) sensor -G79- and
the Sender -2- for accelerator pedal position -
G185- are located at the accelerator pedal and
communicate the driver's intentions to the ECM
completely independently of each other. Both
sensors are stored in one housing.

Test sequence

- Connect VAS5051 tester or VAG1551 scan tool
and select control module for engine electronics
using "address word" 01 Page 01
-10
. Ignition
must remain switched on.
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 display group number XXX

When indicated on display
- Press buttons -0-, -6- and -2- to select "display group number 062" and
press -Q- button to confirm input.
Read Measuring Value Block 62
1
2
3
4

Indicated on display
- Check specified values for E-gas potentiometer voltages in display
fields 3 and 4.
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ge 27 of 51 Electronic En
gine Power Control
(EPC
) (E-Gas
), checkin
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24-135


Display fields

1 2 3 4
Display group 062: E-Gas potentiometer voltages
Display xx % xx %
xx %
xx %
Indicated Throttle valve angle
(angle sensor 1) Throttle valve angle
(angle sensor 2) Sensor 1 for
Pedal position Sensor 2 for
Pedal position
Specified value 3 to 93 % 97 to 3 %
12 to 97 %
4 to 49 %
Note:
Engine Control Module (ECM) calculates the
voltage values of the angle sensors in percent
relative to 5 volts and displays these percentage
values. (5 volts supply voltage represents 100
%).

- Observe display field 3 and 4.

- Slowly depress accelerator pedal completely.
Percent indication in display field 3 must rise
uniformly. The tolerance range 12 to 97% is not
used completely during this.
Percent indication in display field 4 must also rise
uniformly. In the process, the tolerance range of
4 to 49% is not completely utilized.
Pa
ge 28 of 51 Electronic En
gine Power Control
(EPC
) (E-Gas
), checkin
g
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play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU06.24.4

If specified values are not obtained: - Also check signal wires.
- Check wire connections from Engine Control Module (ECM) to sensors
for accelerator pedal position.
Pa
ge 31 of 51 Electronic En
gine Power Control
(EPC
) (E-Gas
), checkin
g
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play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU06.24.4

24-138

Checking wire connections

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

If no malfunctions are found in wires:
Repair Manual, Fuel Supply System, Repair Group 20
- Check following wire connection for open circuit and short circuit to
Ground (GND) and B+:
Harness connector
Terminal
VAG1598/31 test box
Socket
1 72
2 73
3 36
4 35
5 33
6 34
- Repair open circuit or short circuit if necessary.
- Replace accelerator pedal position sensor.
Pa
ge 32 of 51 Electronic En
gine Power Control
(EPC
) (E-Gas
), checkin
g
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p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU06.24.4

24-139

Kick down function, adapting

If the sensor for accelerator pedal position or the
Engine Control Module (ECM) is replaced on a
vehicle with automatic transmission, the kick
down function must be adapted.

Special tools and equipment

or
Requirements
Procedure
VAS5051 with VAG5051/1VAG1551 with VAG1551/3ANo DTCs in DTC memory, check DTC memory Page 01
-16
.
Engine not running, ignition switched on.
- Connect VAS5051 tester or VAG1551 scan tool and select control
module for engine electronics using "address word" 01 Page 01
-10
.
Ignition must remain switched on.
Pa
ge 33 of 51 Electronic En
gine Power Control
(EPC
) (E-Gas
), checkin
g
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play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU06.24.4

24-144

Note:
For safety reasons, the instruction from the
accelerator pedal sensor (potentiometer) to the
ECM to open the throttle valve is suppressed
when brake is being operated. This requires the
brake light switch signal and also the brake pedal
switch signal in the control module. If brake pedal
is operated with accelerator pedal constantly
depressed, engine is immediately regulated
down to idle speed. A faulty switch can lead to
undesired regulation.

Test sequence

- Connect VAS5051 tester or VAG1551 scan tool
and select control module for engine electronics
using "address word" 01 Page 01
-10
. Ignition
must remain switched on.
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-, -6- and -6- to select "display group number 066" and
press -Q- button to confirm input.
Pa
ge 39 of 51 Electronic En
gine Power Control
(EPC
) (E-Gas
), checkin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU06.24.4

24-145

Read Measuring Value Block 66
1
2
3
4

Indicated on display
- Check brake light/brake pedal switch in display field 2.

Display fields

1 2 3 4
Display group 066: Signals to Engine Control Module (ECM)
Display xxx km/h
XXXX xxx km/h XXXX
Indicated ACTUAL speed
Switch positions SPECIFIED speed Switch positions
Functional range
XX00
XX11
Specified value
XX00
(with brake pedal not operated)

XX11
(with brake pedal operated)
Note
Value:X = no significance.
Switch points slightly offset
Pa
ge 40 of 51 Electronic En
gine Power Control
(EPC
) (E-Gas
), checkin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU06.24.4