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Ignition system, glow plug system > < Engine control unit

Leon Mk1

Intake manifold pressure sender: checking
Intake manifold pressure sender: checking
Special tools and workshop equipment required
   
t  Hand multimeter -V.A.G 1526 A- or multimeter -V.A.G 1715-
  W00-0431
t  Fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- with cable -V.A.G 1551/3B-
t  Auxiliary measuring set -V.A.G 1594 C-
t  Test box -V.A.G 1598/18-
t  Current flow diagram
Checking process
–  Connect fault reader -V.A.G 1551- (-V.A.G 1552-). Start engine and enter “Address code” 01 to select engine control unit. (Fault reader: Connecting and selecting the engine control unit → Chapter.)
  W00-0459
Indicated on the display:
–  Press keys 0 and 8 for the function “Read measured value block” and confirm entry with the Q key.
  
Rapid data transfer                 HELP
Select function XX
Indicated on the display:
–  Press keys 0, 0 and 3 for “Display group number 3” and confirm entry with the Q key.
  
Read measured value block           HELP
Input display group number XXX
Indicated on the display:
(1…4 = display zones)
–  Read off the displayed value for engine load in display zone 2 and note this value.
–  Briefly open throttle valve. The engine load value must increase briefly.
If the display remains constant at 0% or 100 %:
  
Read measured value block 3           ->
         1         2         3         4
IndicatedCauseContinuation of check
0 %Open circuit or short circuit to earth →  
100 %Short circuit to positive →  

Continue checking if 0 is indicated %:
   
–  Pull connector -1- off intake manifold pressure sender -G71- with intake air temperature sender -G42--2- (engine stalls).
–  Bridge connector contacts 3+4.
Indication of 100 %:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Renew the intake manifold pressure sender -G71- with intake air temperature sender -G42--2-, → Item
Indication of 0 %:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
  N24-0306
–  Connect test box -V.A.G 1598/18- to control unit wiring harness.
–  Check wiring between test box and connector for open circuit using current flow diagram.
  N24-0334
ContactTest box -V.A.G 1598/18-, socket
337
418
Wire resistance: 1,5 Ω max.

–  Also check wiring contact 4 for short circuits to earth and contact 1.
   Specification: ∞ Ω
If no wiring fault is detected:
–  Renew engine control unit → Chapter
Continue checking if 100 is indicated %:
   
–  Pull connector -1- off intake manifold pressure sender -G71- with intake air temperature sender -G42--2- (engine stalls).
Indication of 0 %:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Renew the intake manifold pressure sender -G71- with intake air temperature sender -G42--2-, → Item.
Indication of 100 %:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Remove the connector of the engine control unit.
–  Check the wiring to the control unit connector at 4-pin connector, contact 4, for short circuits to wire contact 3 and battery positive.
   Specification: ∞ Ω
If no wiring fault is detected:
–  Renew engine control unit → Chapter
  N24-0305

Ignition system, glow plug system > < Engine control unit