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Testing the voltage supply of the throttle valve control unit J338 > < Testing throttle valve control unit J338

Fabia Mk1

Testing angle sender for throttle valve drive
Testing angle sender for throttle valve drive
The throttle valve drive angle senders -G187- and -G188- inform the engine control unit of the position of the throttle valve. Both angle senders are located in the throttle valve control unit -J338 -.
–  Connect vehicle diagnosis system, measurement and information system - V.A.G 1552-. Switch ignition on and select “address word” 01 Engine electronics → Chapter.
–  Select function 08 “Read measured value block” and display group number 062.
Engines with engine identification characters AUA, AUB, BBY, BBZ, BKY
   
Readout on display:
Engines with engine identification characters BUD
  
Reading measured value block 62     ->
     7%        8%      14%           14%
Readout on display:
Continued for all engines
–  Test the values for the electronic throttle potentiometer voltages.
  Note
The engine control unit converts the voltage values in percentage (in relation to 5 Volts). (5 Volts power supply correspond to 100%).
–  Observe display fields 1 and 2.
–  Slowly press the accelerator pedal fully down.
The percentage indication in display field 1 must rise gradually. The tolerance range 0…100 % is not fully used up.
The percentage indication in display field 2 must drop gradually. The tolerance range 100…0 % is not fully used up.
  Note
t  The reason why the display in display field 1 rises and the display in display field 2 drops lies in the opposition of the potentiometer (angle sender) in the throttle valve control unit -J338-.
t  This means that the voltage tapping of angle sender 1 runs towards the 5 Volts (the further the throttle valve is opened the greater the voltage; the percentage indication rises).
t  The voltage tapping of angle sender 2 runs away from the 5 Volts towards 0 Volt (the further the throttle valve is opened the lower the voltage: the percentage indication drops).
If the display does not occur as described:
–  Select function 06 “End output” and confirm with Q.
–  Switch off ignition.
Engines with engine identification characters AUA, AUB, BBY, BBZ, BKY
–  Remove engine cover with air filter → Chapter.
Engines with engine identification characters BUD
–  Remove the air filter housing → Chapter
Continued for all engines
–  Disconnect the plug from the throttle valve control unit -J338-.
  
Reading measured value block 62     ->
   16,0%      83.2%      14%         14%
–  Measure the throttle valve drive resistance on the throttle valve control unit -J338- between contacts 3+5.
   Specified value: 3…200 Ω
If the specified value is not reached:
–  Replace the throttle valve control unit -J338-.
If the specified value is reached:
–  Test the voltage supply and the wiring of the throttle valve control unit -J338 - → Chapter. Pay special attention to the plug connections that may be loose or corroded.
–  Inspect the accelerator pedal position sender → Chapter.
  S24-0583

Testing the voltage supply of the throttle valve control unit J338 > < Testing throttle valve control unit J338