1996 AUDI A4 AWM Engine Additional Signals Checking Workshop Manual

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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24-171


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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24-172


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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24-173

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 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
Control module for
Airbag -J234-
Terminal
67 Electrical Wiring Diagrams,
Troubleshooting & Component
Locations
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24-174

- Repair open circuit or short circuit if
necessary.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations If no malfunctions are found in wire:

- Check DTC memory of control module for
airbag:

Repair Manual, Body On Board Diagnostic
(OBD), Repair Group 01; On Board Diagnostic (OBD) of airbag system BAE (basic trigger unit) with side airbag; DTC memory, checking

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24-175

Consumption signal for board
computer, checking


Note:
The consumption signal is transferred from the
Engine Control Module (ECM) to the instrument
cluster via CAN-bus. Check data exchange
between Engine Control Module (ECM) and
other CAN capable control modules Page 24
-
178

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24-176

Wire for fuel level signal, checking


Notes:

The signal helps with cause localization when
certain malfunctions are recognized (e.g.
combustion misfires).
The fuel level signal is transferred from the
instrument cluster to the Engine Control Module
(ECM) via CAN-bus. Check data exchange
between Engine Control Module (ECM) and
other CAN capable control modules Page 24
-178

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24-177

Signal for rough terrain recognition,
checking


Notes:

When the ABS/EDL control module recognizes
that a wheel is spinning, the ABS/EDL control
module generates the rough terrain signal.
When the Engine Control Module (ECM)
recognizes the rough terrain signal, combustion
misfire recognition is switched off in the Engine
Control Module (ECM).
Only check the rough terrain signal if the
malfunction "18014 (P1606) rough terrain
info/engine torque from ABS cont. mod.
Electrical malfunction in circuit" is stored DTC
memory. It is possible that the malfunction
"Combustion misfire" is also stored in DTC
memory as a side effect and it can be
disregarded.
The rough terrain signal is transferred from the
ABS/EDL control module to the Engine Control
Module (ECM) via CAN-bus. Check data
exchange between Engine Control Module
(ECM) and other CAN capable control modules
Page 24
-178

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