diagram AUDI A6 1995 C5 / 2.G ATQ Engine Additional Signals Testing Workshop Manual

24-166

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 ECM, do not connect ECM Page 24
-17
.

- 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 binder

- Repair open circuit or short circuit if
necessary.
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24-167

Consumption signal for on board
computer, checking


Notes:

The consumption signal is calculated by the
ECM from the injection time and directed to the
on board computer via terminal 81 of the ECM.
Consumption signal, checking

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder
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24-168

Vehicle speed signal, checking


Notes:

The vehicle speed signal is generated by the
Vehicle Speed Sensor (VSS) -G68- (at
transmission) and 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:

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder
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24-170

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

- 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).
If LED does not blink:

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

Test box
VAG1598/31
Socket
Instrument cluster

Terminal
54 Electrical Wiring Diagrams,
Troubleshooting & Component
Locations binder

- Repair open circuit or short circuit if
necessary.
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24-171

Wire for fuel level signal, checking


Notes:

The Engine Control Module (ECM) receives the
fuel level signal from the instrument cluster.
The processed signal enters at terminal 30 of
the ECM and is used to determine the cause of
certain recognized malfunctions (e.g.
combustion misfires).

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

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

Test box
VAG1598/31
Socket
Instrument cluster

Terminal
30 Electrical Wiring Diagrams,
Troubleshooting & Component
Locations binder

- Repair open circuit or short circuit if
necessary.
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24-174

- Depress gas pedal completely (swiftly) and then
release it (brief acceleration).


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).
If indications do not resemble description:

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

- 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 binder

- Repair open circuit or short circuit if
necessary.

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24-177

- 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
40 Electrical Wiring Diagrams,
Troubleshooting & Component
Locations binder

- Repair open circuit or short circuit if
necessary.

- If there are no malfunctions in the wiring, check
function of A/C system.

Repair Manual, Heating & Air Conditioning,
Repair Group 01

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24-182
If LED does not light up:

- Check wire connection from terminal 1 or 3 of
connector for open circuit and short circuit to
Ground (GND):

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder
- Repair open circuit or short circuit if
necessary.
If LED lights up:

Checking activation

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

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

Harness connector
Terminal
VAG1598/31 test box
Socket
2 56
4 55
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24-186
If specified value is obtained:

Checking voltage supply

If LED does not light up:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
binder - Connect VAG1527B voltage tester as follows:Harness connector
Terminal
Measure to
1 Chassis Ground (GND)
- Switch ignition on.

LED must light up.
- Check wire connection from terminal 1 of connector to fuse for open
circuit and short circuit to Ground (GND):
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24-188

Wire for crash signal, checking

The Engine Control Module (ECM) receives the
crash signal ("Crash shut-off was triggered") from
the airbag control module.
When the airbag control module sends the crash
signal to the ECM (during an accident or when
output DTM is being performed for the airbag
system), the ECM switches the Fuel Pump (FP)
off. This means that the engine will stop running
but can be started again afterward (e.g. to
remove vehicle from danger).

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


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

Test box
VAG1598/31
Socket
Control module for
Airbag -J234-
Terminal
67 Electrical Wiring Diagrams,
Troubleshooting & Component
Locations binder
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