battery AUDI A6 2000 C5 / 2.G ATW Engine Oxygen Sensor Control Workshop Manual
Page 32 of 37
24-102
      
- Start engine. 
     
 
Specification: approx. battery voltage, 
possibly fluctuating 
     
Note:  
     
At certain operating points, the ECM "pulses" 
the Ground (GND) for oxygen sensor heating. 
This means that the Ground (GND) is 
constantly switched on and off at these points. 
It is therefore possible that the voltage 
displayed on the tester will fluctuate. 
     When the ECM switches oxygen sensor heating 
on and off can be observed, if necessary, via 
the function "read measuring value block" 
display group number 041. 
      If there is no voltage:  
     
-  Connect multimeter for voltage measurement as 
follows: 
     
Harness connector  
Terminal  
Measure to  
1 (B+)   Vehicle Ground (GND)  
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Page 33 of 37
     
-  Operate starter briefly.
     
 
Specification: approx. battery voltage
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Page 34 of 37
24-103
       If there is no voltage again:  
     
-  Check wire connection from terminal 1 of 
connector to Fuel Pump (FP) relay via fuse for 
open circuit: 
     
       Electrical Wiring Diagrams, Troubleshooting & 
Component Locations         If voltage supply is OK:  
    
If there is no voltage:  -  Connect multimeter for voltage measurement as follows:Harness connector  
Terminal  
Measure 
to  
2 (Ground -GND- activation of Engine Control Module -
ECM-)  B+  
- Start engine.
 
Specification: approx. battery voltage, possibly fluctuating
-  Switch ignition off.
-  Connect VAG1598/31 test box at wiring harness to Engine Control 
Module (ECM), do not connect ECM   Page 24
-19
 . 
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