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Test brake light switch F and brake pedal switch F47 > < Testing signals from the air conditioning system

Fabia Mk1

Testing the speed signal
Testing the speed signal
The speed signal is generated by the speedometer sender -G22- and is produced in the dash panel insert. The produced signal enters at contact 20 of the engine control unit.
Special tools and workshop equipment required
t  Vehicle system tester -V.A.G 1552-
t  Diagnostic cable -V.A.G 1551/3-
t  Hand multimeter (e.g. -V.A.G 1526 A-)
t  Adapter cable set (e.g. -V.A.G 1594 A-)
t  Test box -V.A.G 1598/31-
Test condition
l  Function and display of the speedometer O.K., fault finding → Electrical System; Rep. Gr.90
Test sequence
  Note
t  The vehicle must be driven in order to test the speed signal. The assistance of a second person is required.
t  Comply with the safety instructions for test drives → Chapter.
–  Connect vehicle system tester - V.A.G 1552-. Leave the engine on and select the engine control unit with “Address word” 01 → Chapter.
–  Select function 08 “read measured value block” and display group number 006.
   
–  Readout on display:
–  Determine by means of a test drive whether the driving speed is displayed in display field 1.
  Caution
Secure the vehicle system tester to the rear seat and operate from that position.
–  If the driving speed is not displayed:
–  Select function 06 “End output” and confirm entry with Q.
–  Switch off the ignition.
–  Connect the test box -V.A.G 1598/31 - to the wiring loom on the engine control unit → Chapter.
–  Connect the handheld multimeter to measure the voltage between bushes 4/5+20 of the test box -V.A.G 1598/31 -.
–  Switch on the ignition.
–  Raise vehicle until the front left wheel is free.
–  Turn the left front wheel manually and observe the voltage display on the handheld multimeter.
   Specified value: fluctuating between 0 and 4 V.
If the display does not fluctuate:
–  Check the following wiring for open circuit or short circuit to earth or positive:
  
Reading measured value block         6   ->
0 km/h       000       000000         255
Test box - V.A.G 1598/31-, bushDash panel insert contact
20 → Current flow diagrams, Electrical fault finding and Fitting locations

–  If necessary eliminate wire interruption or short-circuit.
   

Test brake light switch F and brake pedal switch F47 > < Testing signals from the air conditioning system