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Signals from/to air conditioning system: checking > < Additional signals checking

Leon Mk1

Speed signal checking
Speed signal checking
Special tools and workshop equipment required
t  Fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- with cable -V.A.G 1551/3B-
t  Test box -V.A.G 1598/31-
t  Hand multimeter -V.A.G 1526 A- or multimeter -V.A.G 1715-
t  Adapter set -V.A.G 1594 C-
t  Current flow diagram
Check conditions
l  Battery voltage at least 11.5 V.
l  Speedometer must be OK. Checking the speedometer → Electrical system; Rep. Gr.90.
l  No faults must be stored in fault memory → Chapter, Fault memory: consulting.
Test sequence
  Note!
To check the speed signal the vehicle must be driven. To do this a second person is necessary.
  Caution
Secure fault reader to rear seat and operate from this position.
Observe the valid safety precautions when carrying out a road tes → Chapter.
–  Connect fault reader -V.A.G 1551/V.A.G 1552-. Then switch ignition on and select engine control unit with the “Address code” 01. (Fault reader: Connecting and selecting the engine control unit → Chapter).
   
Indicated on display:
–  Press keys 0 and 8 for the function “Read measured value block” and confirm entry with Q -key.
  
Rapid data transfer                 HELP
Select function XX
Indicated on display:
–  Press keys 0, 0 and 5 for “Display group number 5” and confirm entry with Q -key.
  
Read measured value block           HELP
Input display group number XXX
Indicated on display: (1...4 = Display fields)
–  Carry out test drive with a 2nd person to observe display.
–  Observe figure displayed in display field 3:
   Specification: approx. driven speed
–  Press → -key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q -key.
–  Switch off ignition.
If no speed is displayed:
  
Read measured value block 5           ->
       1         2         3         4
–  Connect test box -V.A.G 1598/31- to control unit wiring harness. The engine control unit remains disconnected.
–  Connect multimeter to measure voltage between test box sockets 62 (terminal 15) +54 (speed signal).
–  Switch on ignition.
–  Raise front left side of vehicle.
–  Rotate front left wheel by hand and observe voltage display
   Specification: between 1 and at least 4 Volt fluctuating
  Note!
If necessary, hold the front right wheel to prevent it from turning.
If the display does not fluctuate:
–  Check wiring to speedometer/speedometer sender → Current flow diagrams, Electrical fault finding and Fitting locations.
  N24-0943

Signals from/to air conditioning system: checking > < Additional signals checking