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Test signal of PAS pressure switch > < Testing the speed signal

Octavia Mk1

Check signal for gearbox intervention during gearshifts
Check signal for gearbox intervention during gearshifts
  Note
t  By means of this signal from the automatic gearbox control unit, the ignition angle is briefly reduced (torque reduction) depending upon the speed and engine speed during gearshifts of the automatic gearbox, in order to avoid the jerky gear change.
t  For vehicles ► 07.97, the signal is a rectangular signal, which arrives at contact 23 at the engine control unit.
t  For vehicles 08.97 ►, the signal is a rectangular signal, which arrives via the data BUS at contact 23 at the engine control unit.
t  Due to the very short signal, the request for ignition angle relief from -V.A.G 1552- is not always detected.
Special tools and workshop equipment required
t  Handheld multimeter, e.g. -V.A.G 1526 A -
t  Vehicle system tester -V.A.G 1552 - with cable -V.A.G 1551/3-
t  Measuring tool set -V.A.G 1594 A -
t  Test box -V.A.G 1598/22-
Procedure
–  Connect vehicle system tester -V.A.G 1552- → Chapter.
–  Conduct a test drive and select the function 08 “read measured value block” and display group 001 → Chapter.
  WARNING
The -V.A.G 1552- should be operated by a second person.
   
The following appears in the display:
Specified value: X 0 X X X X X X = without gearbox intervention
Specified value: X 1 X X X X X X = gearbox intervention
Value: X = no meaning
  Note
If the automatic gearbox control unit requests an ignition angle relief, the display quickly jumps from “0” to “1”.
–  The wiring to the automatic gearbox control unit is monitored by the gearbox self-diagnosis (fault code 00545).
During gearshifts, if no read-out for the torque reduction is performed in the measured value block or the fault code 00545 (in the automatic gearbox control unit) is shown:
For vehicles ► 07.97
–  Connect the test box -V.A.G 1598/22 - to the wiring loom of the engine control unit → Chapter.
–  Test wiring of contact 23 of engine control unit for interruption and/or short-circuit → Current flow diagrams and Fitting locations.
For vehicles 08.97 ►
–  Test databus drive → Chapter.
  
Reading measured value block 1                      ->
850/rpm    90°C    0.80 V  00000010

Test signal of PAS pressure switch > < Testing the speed signal