2000 AUDI A4 display

24-164

Engine speed signal, checking


Note:
The engine speed signal is output at terminal 37
of the Engine Control Module (ECM). The signal
is used, among other things, for RPM display in
the instrument cluster.

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

- Check the following wire connection for open
circuit and short circuit to Ground (GND) and B+:

Test box
VAG1598/31
Socket
Instrument cluster

Terminal
37 Electrical Wiring Diagrams,
Troubleshooting & Component
Locations

- Repair open circuit or short circuit if
necessary.
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24-165

Vehicle speed signal, checking


Notes:

The vehicle speed signal is generated by the
speedometer Vehicle Speed Sensor (VSS) -
G22- (at transmission) and is processed in the
instrument cluster.
The processed signal enters at terminal 54 of
the ECM and is used for idle stabilization and
tip-in shock reduction during shifting.

Test requirement:
Function and display of speedometer OK.
Troubleshooting:

Repair Manual, Electrical Equipment, Repair
Group 90; Instrument cluster; Speed signal, checking


Test sequence

WARNING!

To reduce the risk of accident during road
tests, always observe safety precautions
Page 24
-1 .
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Display on VAS5051:
- Select diagnostic function "08 - Read Measuring Value Block" in
selection -1-.

Display on VAS5051:
1 - Enter display group Max. input value = 255
- Select function "005" in button field -2- for "display group number 005"
and press Q button to confirm input.
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24-167


Display on VAS5051:
- Determining via road test whether vehicle speed is displayed in display
field -3-.
- If vehicle speed is not display, lift vehicle -if possible using a vehicle lift-
until front left wheel is free.
- Connect VAG1598/31 test box at wiring harness to Engine Control
Module (ECM), do not connect ECM Page 24
-19
.
- Connect VAG1527B voltage tester to sockets 3 (B+) and 54 (VSS) of
VAG1598/31 test box.
- Switch ignition on and turn front left wheel by hand.

LED must blink (very brief blink signal).
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24-170

Test requirements:

A/C system OK
No DTCs in DTC memory of Engine Control
Module (ECM).
Vehicle at room temperature (warmer than
+15 C).

Test sequence

- Connect VAS5051 tester Page 01
-7 and
select vehicle system "01 - Engine electronics".
Engine must run at idle for this.

Display on VAS5051:
- Select diagnostic function "08 - Read Measuring Value Block" in
selection -1-.
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Display on VAS5051:
1 - Enter display group Max. input value = 255
- Select function "050" in button field -2- for "display group number 050"
and press Q button to confirm input.

Display on VAS5051:
- Switch A/C system off.

Specified value in display field -4-: Compr. OFF
- Switch A/C system on using "Auto" button and adjust A/C system to
maximum cooling or heating power. Compressor must run.
Specified value in display field -4-: Compr. ON
- Depress gas pedal completely (swiftly) and then release it (brief
acceleration).
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Display on VAS5051:
If indications do not resemble description:
Repair Manual, Heating & Air Conditioning, Repair Group 01; On Board Diagnostic (OBD) of A/C system

Specified value in display field -4-: Indication jumps for a few
seconds from "Compr. ON" to "Compr. OFF" (compressor is
switched off when vehicle accelerates).
- Connect VAG1598/31 test box at wiring harness to Engine Control
Module (ECM), do not connect ECM Page 24
-19
.
- Check the following wire connection for open circuit and short circuit to
Ground (GND) and B+:
Test box
VAG1598/31
Socket
A/C control
head -E87-
Terminal
41 Electrical Wiring Diagrams, Troubleshooting &
Component Locations
- Repair open circuit or short circuit if necessary.
- If there are no malfunctions in the wiring, check function of A/C system.
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24-179


Display on VAS5051:
- Select diagnostic function "08 - Read Measuring Value Block" in
selection -1-.

Display on VAS5051:
Note:
Measuring value blocks 125 and 126 indicate the participants in the
powertrain data-BUS. 1 - Enter display group Max. input value = 255
- Select function "125" in button field -2- for "display group number 125"
and press Q button to confirm input.
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