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Measured value blocks > < Final control diagnosis

Polo Mk3

Performing final control diagnosis
Performing final control diagnosis
Special tools and workshop equipment required
t  Fault reader -V.A.G 1551-
t  Diagnosis lead -V.A.G 1551/3C-
Test requirements for vehicles with air conditioning system
l  Vehicle at room temperature (warmer than + 15 °C)
l  Air conditioning system switched on
l  Select lowest temperature and highest blower speed
The final control diagnosis activates the following components in the stated sequence:
1 - Exhaust gas recirculation valve -N18-
2 - Conditioner compressor interruption
3 - Charge pressure control solenoid valve -N75-
4 - Variable intake manifold flap change-over valve -N239-
5 - Glow period warning lamp -K29-
6 - Glow plug relay -J52-
7 - Low heat output relay -J359-
8 - High heat output relay -J360-
  Note
t  Activation of individual control elements is limited to 30 secs. but can be stopped at any time by pressing the → button.
t  The ignition must be switched off before repeating the final control diagnosis.
Procedure
–  Connect fault reader -V.A.G 1551- and select engine electronics control unit with “address word 01”. Engine must be idling. (Connecting fault reader and selecting engine electronics control unit → Chapter.)
   
Indicated on display:
–  Operate fault reader taking into account the information on the display:
–  Press buttons 0 and 3 for function “final control diagnosis”.
  
Rapid data transfer                 HELP
Select function XX
Indicated on display:
–  Confirm entry with Q button.
  
Rapid data transfer                    Q
03-Final control diagnosis
Indicated on display:
The valve must click.
  Note
The valve clicking cannot be heard because of engine noises and can therefore only be felt by touch.
If the valve does not click:
–  Check exhaust gas recirculation system → Chapter
–  Press the → button.
  
Final control diagnosis               ->
Exhaust gas recirculation valve N18
Indicated on display:
Air conditioner compressor switch-off is checked.
The test step is also recalled on vehicles without air conditioner system.
The air conditioner compressor must stop within 5 seconds (visual check) then start approx. every 5 seconds and then stop again.
If the conditioner compressor is not switched off:
–  Check signals from/to air conditioning system → Chapter
–  Press the → button.
  
Final control diagnosis               ->
Conditioner compressor interruption
Indicated on display:
Charge pressure control solenoid valve -N75- must click.
  Note
The clicking of the valve is difficult to hear and is therefore best checked by touch.
If the charge pressure control solenoid valve -N75- does not click:
–  Check charge pressure control solenoid valve -N75- → Chapter.
–  Press the → button.
  
Final control diagnosis               ->
Charge pressure control solenoid valve N75
Indicated on display:
The engine must stop.
If the engine does not stop:
–  Check intake manifold flap changeover → Chapter
–  Press the → button.
  
Final control diagnosis               ->
Var. intake manif. flap change-over valve N239
Indicated on display:
Glow period warning lamp -K29- must flash.
If glow period warning lamp -K29- does not flash:
–  Check glow period warning lamp -K29-: → Current flow diagrams, Electrical fault finding and Fitting locations
–  Press the → button.
  
Final control diagnosis               ->
Glow period warning lamp K29
Indicated on display:
Glow plug relay -J52- must click.
If the glow plug relay -J52- does not click:
–  Check glow plug relay -J52- → Current flow diagrams, Electrical fault finding and Fitting locations
–  Press the → button.
  
Final control diagnosis               ->
Glow plug relay J52
Indicated on display:
The Low heat output relay -J359- must click.
If low heat output relay -J359- does not click:
–  Check low heat output relay -J359- → Current flow diagrams, Electrical fault finding and Fitting locations.
–  Press the → button.
  
Final control diagnosis               ->
Low heat output relay J359
Indicated on display:
The high heat output relay -J360- must click.
Switching on and off the relay can also be observed as the interior light becomes brighter and darker as a result of the glow plug high power consumption.
If high heat output relay -J360- does not click:
–  Check high heat output relay -J360- → Current flow diagrams, Electrical fault finding and Fitting locations.
–  Press the → button.
  
Final control diagnosis               ->
High heat output relay J360
Indicated on display:
–  Press buttons 0 and 6 for function “End output” and confirm entry with Q button.
–  Switch off ignition.
Now the final control test is concluded.
  
Rapid data transfer                 HELP
Select function XX

Measured value blocks > < Final control diagnosis