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Testing voltage supply of throttle valve control unit J338 > < Inspecting 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 system tester -V.A.G 1552-. Switch ignition on and select “address word” 01 Engine electronics → Chapter.
–  Enter function 08 “Read measured value block” and select display group number 062.
   
Readout on display:
–  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.
  
Reading measured value block         62   ->
15,0 %     75,0 %     15,0 %     7,0 %
–  Remove engine cover as follows:
t  Release logo -2- and cap -3-.
t  Release nuts -4- (5 Nm).
t  Pull out oil dipstick -6-.
t  Remove engine cover -1- towards the top (do not unscrew cap -5-).
  S10-0138
–  Unplug connectors from the throttle valve control unit - J338-.
–  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 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.
–  Check accelerator pedal position sender → Chapter.
  S24-0274

Testing voltage supply of throttle valve control unit J338 > < Inspecting Throttle valve control unit J338