check engine AUDI A4 1999 B5 / 1.G AWM Engine Additional Signals Checking Workshop Manual
[x] Cancel search | Manufacturer: AUDI, Model Year: 1999, Model line: A4, Model: AUDI A4 1999 B5 / 1.GPages: 25, PDF Size: 0.13 MB
Page 2 of 25

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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Page 4 of 25

- Connect VAS5051 tester Page 01
-7 and
select vehicle system "01 - Engine electronics".
Engine must run at idle for this.
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Page 6 of 25

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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Page 8 of 25

24-169
A/C compressor shut-off, checking
Notes:
The A/C compressor signal communicates to
the ECM that the compressor will be switched
on in 140 ms.
The Engine Control Module (ECM) can switch
off the A/C compressor via the same wire
connection.
Engine Control Module (ECM) switches off A/C
compressor:
-- during hard acceleration (Wide Open
Throttle 1st gear)
-- in emergency mode (emergency
operation)
-- after initiating basic setting (function 04)
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Page 9 of 25

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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Page 11 of 25

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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Page 12 of 25

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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Page 14 of 25

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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Page 15 of 25

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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Page 16 of 25

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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