wiring AUDI A4 1995 B5 / 1.G APB Engine Additional Signals Checking Workshop Manual
[x] Cancel search | Manufacturer: AUDI, Model Year: 1995, Model line: A4, Model: AUDI A4 1995 B5 / 1.GPages: 37, PDF Size: 0.14 MB
Page 1 of 37

24-179
 
     
Additional signals, checking 
     
Engine speed (RPM) signal, checking 
 
     
Note:  
     The engine speed signal is taken from terminal 
37 on the Engine Control Module (ECM). The 
signal is used for various functions including the 
RPM display in the instrument cluster. 
    
 Electrical Wiring Diagrams, Troubleshooting & Component Locations    -  Connect VAG1598/31 test box to wiring harness for engine control 
module. Do not connect to the engine control module itself   Page 24
-
20
 . 
-  Check wiring from test box socket 37 to instrument cluster according to 
wiring diagram for an open circuit. 
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Page 2 of 37

24-180
      
Fuel consumption signal for on-board 
computer, checking
 
     
Notes:  
     
The fuel consumption signal is calculated by the 
engine control module (on the basis of the 
injection period) and passed on to the on-board 
computer. The fuel consumption signal is taken 
from terminal 81 on the Engine Control Module 
(ECM). 
     Checking fuel consumption signal
     
       Electrical Wiring Diagrams, Troubleshooting & 
Component Locations   
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Page 3 of 37

24-181
      
Coolant temperature signal, checking
 
     
Notes:  
     
The engine control module receives the coolant 
temperature signal from the instrument cluster. 
When the signal is received, the charge 
pressure is reduced to prevent the engine from 
overheating. 
    
 Electrical Wiring Diagrams, Troubleshooting & Component Locations    -  Connect VAG1598/31 test box to wiring harness for engine control 
module. Do not connect to the engine control module itself   Page 24
-
20
 . 
-  Check wiring from test box socket 19 to instrument cluster according to 
wiring diagram for an open circuit. 
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Page 6 of 37

24-183
      
-  Take vehicle for a test drive and check whether 
vehicle speed appears in display field 3. 
     
-  If vehicle speed does not appear, raise the 
vehicle (preferably using a lift) until front left 
wheel is clear of the ground. 
    
 Electrical Wiring Diagrams, Troubleshooting & Component Locations    -  Connect VAG1598/31 test box to wiring harness for engine control 
module. Do not connect to the engine control module itself   Page 24
-
20
 . 
-  Connect diode test lamp between socket 3 (B+) and socket 54 (vehicle 
speed signal). 
-  Switch ignition on and turn front left wheel by hand.
   The diode test lamp should flash (very brief flashes).
-  If diode test lamp does not flash, check for open circuit or short to B+ 
or Ground (GND) in wiring between instrument panel and terminal 54 
on engine control module connector. 
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Page 7 of 37

24-184
      
Fuel tank level signal, checking
 
     
Note:  
     
The Engine Control Module (ECM) receives the 
fuel tank level signal from the instrument 
cluster. 
     The processed signal enters on terminal 30 the 
Engine Control Module (ECM) and is used to 
determine certain malfunctions (e.g.: misfire) 
     
-  Connect VAG1598/31 test box to wiring harness 
for engine control module. Do not connect to the 
engine control module itself   Page 24
-20
 . 
     
-  Check wiring from test box socket 30 to 
instrument cluster according to wiring diagram 
for an open circuit and short circuit to B+/Ground 
(GND). 
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Page 12 of 37

24-189
       If specifications are not met:  
     
Check voltage supply  
     
-  Connect VAG1527 B between following sockets 
on harness connector: 
     
Harness connector 
terminal  
Measure 
against  
1   Ground (GND)  
     
 
The LED must come on
     Harness connector 
terminal  
Measure 
against  
3   Ground (GND)  
     
-  Switch ignition on.
     
 
The LED must come on
      If LED does not come on:  
     
-  Check wiring connection from terminal 1 or 3 of 
connector for open circuit (fuse) or short circuit 
to Ground (GND). 
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Page 13 of 37

     
       Electrical Wiring Diagrams, Troubleshooting & 
Component Locations        
-  If necessary eliminate open circuit or short 
circuit to Ground (GND) 
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Page 14 of 37

24-190
       If LED comes on:  
     
Check activation  
     
-  Connect VAG1598/31 test box to wiring harness 
for engine control module. Do not connect to the 
engine control module itself   Page 24
-20
 . 
      Test the following wiring connections for open 
circuits and short to B+ or Ground (GND):  
     
Harness 
connector  
terminal  
VAG1598/31 test box, 
socket  
2   56  
4   55  
     
-  Repair any open/short circuit as necessary.
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Page 20 of 37

24-194
       If specification is obtained:  
     
Check voltage supply  
     
-  Connect VAG1527 B between following sockets 
on harness connector: 
     
Harness connector 
terminal  
Measure 
against  
2   Ground (GND)  
     
-  Switch ignition on.
     
 
The LED must come on
      If LED does not come on:  
     
-  Check wire connection from terminal 2 of 
connector for open circuit (fuse) or short circuit 
to Ground (GND). 
     
       Electrical Wiring Diagrams, Troubleshooting & 
Component Locations   
     
-  If necessary eliminate open circuit or short 
circuit to Ground (GND) 
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Page 21 of 37

24-195
       If LED comes on:  
     
Check activation  
     
-  Connect VAG1598/31 test box to wiring harness 
for engine control module. Do not connect to the 
engine control module itself   Page 24
-20
 . 
      Test the following wiring connections for open 
circuits and short to B+ or Ground (GND):  
     
Harness 
connector  
terminal  
VAG1598/31 test box, 
socket  
1   39  
     
-  Repair any open/short circuit as necessary.
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