volkswagen Workshop Repair Guides

Volkswagen Workshop Service and Repair Manuals

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Checking brake light switch F and brake pedal switch F47 > < Checking speed signal

Golf Mk4

Checking gear change signal from automatic gearbox
Checking gear change signal from automatic gearbox
The engine control unit receives the gear change signal from the gearbox control unit via the data bus line. The engine control unit briefly reduces the amount of fuel injected. This reduces the torque and the gear change jolt.
Special tools and workshop equipment required
t  Fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- with diagnosis cable -V.A.G 1551/3-
t  Adapter cable, 121-pin -V.A.G 1598/31-
t  Hand multimeter -V.A.G 1526C- or multimeter -V.A.G 1715-
t  Auxiliary measuring set -V.A.G 1594C-
t  Current flow diagram
Test procedure
–  Connect fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- and select engine electronics control unit with “address word” 01. Engine must be idling. (Connecting fault reader and selecting engine electronics control unit → Chapter.)
  WARNING
Secure fault reader to rear seat and operate from this position.
   
Indicated on display:
–  Press buttons 0 and 8 for function “Read measured value block” and confirm entry with Q button.
  
Rapid data transfer                 HELP
Select function XX
Indicated on display:
–  Press buttons 0, 0 and 9 for “Display group number 9” and confirm entry with Q button.
–  Carry out road test and when doing this observe display (2nd person necessary).
–  Observe value displayed in display zone 3 on chaging to 2nd gear:
Specification: temporarily less than 51 mg/stroke
  Note
As data transfer is slow, display of the specification may be delayed under certain circumstances.
If the specification is not achieved:
–  Press → button.
–  Press buttons 0 and 6 for function “End data transfer” and confirm entry with Q button.
–  Switch off ignition.
  
Read measured value block           HELP
Input display group number XXX
–  Connect adapter cable, 121-pin -V.A.G 1598/31- to control unit wiring harness.
–  Check line connection from engine control unit to gearbox control unit for open/short circuit → Current flow diagrams, Electrical fault finding and Fitting locations
  N24-0943

Checking brake light switch F and brake pedal switch F47 > < Checking speed signal