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Coolant temperature sender checking > < Intake manifold pressure sender checking

Leon Mk2

Intake air temperature sender checking
Intake air temperature sender checking
  Note!
Only gold-plated contacts may be used when servicing the sender connector contacts
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
t  Chilling spray (commercially available)
Test sequence
–  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 4 for “Display group number 4” and confirm entry with Q -key.
  
Read measured value block           HELP
Input display group number XXX
Indicated on display: (1...4 = Display fields)
–  Read off coolant temperature value in display field 4.
–  If the specification is not obtained:
–  Perform check according to following table:
  
Read measured value block           4 ->
         1         2         3         4
DisplayCauseContinuation of check
-40 °COpen circuit or short to positive →  
120 °CShort to earth →  
Approx. ambient temperature → Note--- →  

1)  If a temperature is displayed which is below the ambient air temperature of the sender, check sender wiring for transfer resistances. Note that sender may be heated by radiated heat when engine is not running..
If display reads -40 °C, continue test as follows:
   
–  Pull 4-pin connector off intake air temperature sender -G42- with intake manifold pressure sender -G71--arrow-.
  N24-0729
–  Bridge connector contacts 1+2 using aux. cables from -V.A.G 1594 C- and observe display.
If the display changes to 120 °C:
–  Press → -key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q -key.
–  Switch off ignition.
–  Renew the intake manifold pressure sender -G71- with intake air temperature sender -G42- → Item.
If the display remains at -40 °C:
–  Press → -key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q -key.
–  Switch off ignition.
  N24-0804
–  Connect test box -V.A.G 1598/31- to control unit wiring harness. The engine control unit remains disconnected.
  N24-0943
–  Check the wiring between test box and 4-pin connector for open circuit using current flow diagram.
   Contact 1+socket 108
   Contact 2+socket 85
   Wire resistance: max. 1.5 Ω
–  Check wiring additionally for short circuit to battery positive.
   Specification: ∞ Ω
If no wiring fault is detected:
–  Renew the intake manifold pressure sender -G71- with intake air temperature sender -G42- → Item.
If display shows 120 °C, continue as follows
  A24-0094
–  Pull 4-pin connector off intake air temperature sender -G42- with intake manifold pressure sender -G71--arrow-.
If the display changes to -40 °C:
–  Press → -key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q -key.
–  Switch off ignition.
–  Renew the intake manifold pressure sender -G71- with intake air temperature sender -G42- → Item.
If the display remains at 120 °C:
–  Press → -key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q -key.
–  Switch off ignition.
  N24-0729
–  Connect test box -V.A.G 1598/31- to control unit wiring harness. The engine control unit remains disconnected.
  N24-0943
–  Check the wiring between test box and 4-pin connector for open circuit using current flow diagram.
   Contact 1+socket 108
   Contact 2+socket 85
   Wire resistance: max. 1.5 Ω
–  Check wiring additionally for short circuit to battery positive.
   Specification ∞ Ω
If no wiring fault is detected:
–  Renew the intake manifold pressure sender -G71- with intake air temperature sender -G42- → Item.
Continuation of test if ambient temperature is shown:
Functional check of sender:
–  Remove air cleaner → Fig..
  A24-0094
–  Remove intake air temperature sender together with intake manifold pressure sender (connector remains connected).
–  Note intake air temperature value in display field 4.
–  Spray sender with commercial chilling agent whilst observing the temperature value. The temperature value should fall.
–  Press → -key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q -key.
–  Switch off ignition.
If the specification is not obtained:
–  Renew the intake manifold pressure sender -G71- with intake air temperature sender -G42- → Item.
  N24-0733

Coolant temperature sender checking > < Intake manifold pressure sender checking