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Intake manifold pressure sender: checking > < Engine operating conditions: checking

Leon Mk2

Throttle valve control unit: checking
   
Throttle valve control unit: checking
  Note!
The basic setting should always be performed whenever the throttle valve control unit -J338- is assembled, removed, or replaced → Chapter.
Special tools and workshop equipment required
t  Hand multimeter -V.A.G 1526 A- or multimeter -V.A.G 1715-
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 idling switch
–  Connect fault reader -V.A.G 1551- (-V.A.G 1552-). Then switch the ignition on and enter “Address code” 01 to select engine control unit. (Fault reader: Connecting and selecting the engine control unit → Chapter.)
   
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 1 for “Display group number 1” 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)
–  Observe the 8 digit number block in display zone 4: (The 4 digits to the right are of no consequence)
   When the throttle is closed, the 4.th position from the left must be a 0:
   Note: 00000000
–  Slowly open throttle valve. After an empty movement a stop is reached. Continuing to open the throttle valve, the 4.th position from the left must jump to 1.
   Note: 00010000
If the specifications are not attained:
–  Remove air filter → Fig..
  
Read measured value block 1           ->
         1         2         3         4
IndicatedCauseContinuation of check
Always 1Open circuit or short circuit to positive →  
Always 0Short circuit to earth →  

Continuation of check when display reads: 1
   
–  Remove connector -1- off throttle valve control unit -2-.
–  Bridge connector contacts 3+7 with aux. cables from -V.A.G 1594 C- and observe display.
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.
–  Replace throttle valve control unit → Item.
Indication of 1:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Check voltage supply of throttle valve control unit and wiring to engine control unit → .
If the voltage supply and wiring are OK:
–  Renew engine control unit → Chapter
Continuation of check when display reads: 0
  N24-0300
–  Remove connector -1- off throttle valve control unit -2-.
Indication of 1:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Replace throttle valve control unit → 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.
–  Check voltage supply of throttle valve control unit and wiring to engine control unit → .
If the voltage supply and wiring are OK:
–  Renew engine control unit → Chapter
Checking throttle valve positioner and throttle valve positioner potentiometer
Test conditions
l  Coolant temperature, 80°C, minimum.
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.)
  N24-0299
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)
–  Check the duty cycle for the throttle positioner in display zone 4. The voltage must fluctuate in the range of 17…29%
If the specification is not obtained:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Remove air filter → Fig..
  
Read measured value block 3           ->
         1         2         3         4
–  Remove connector -1- off throttle valve control unit -2-.
–  Measure throttle valve positioner resistance between terminal connector contacts 1+2
   Specification: 3…200 Ω
–  Check voltage supply of throttle valve control unit and wiring to engine control unit → .
If no fault is detected:
–  Replace throttle valve control unit → Item.
Checking throttle valve potentiometer
Test conditions
l  Coolant temperature, 80°C, minimum.
Checking process
–  Connect fault reader -V.A.G 1551- (-V.A.G 1552-). Then switch the ignition on and enter “Address code” 01 to select engine control unit. (Fault reader: Connecting and selecting the engine control unit → Chapter.)
  N24-0301
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 the angle of throttle valve in display zone 3.The opening angle of throttle valve is indicated in start position
–  Open the throttle valve slowly to full gas, observing the angle displayed in zone 3. The numerical value must increase uniformly within the entire range.
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
If the figure does not increase uniformly:
–  Replace throttle valve control unit → Item.
If the display constantly shows 0 ∠° or is above 100∠°:
–  Remove air filter → Fig..
  
Read measured value block 3           ->
         1         2         3         4
IndicatedCauseContinuation of check
0 ∠°Open circuit or short circuit to positive →  
Above 100 ∠°Short circuit to earth →  

Continue checking if 0 is indicated ∠°:
   
–  Remove connector -1- off throttle valve control unit -2-.
–  Bridge connector contacts 5+7 with auxiliary cables from -V.A.G 1594- and observe display.
Indication of over 100 ∠°:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Replace throttle valve control unit → Item.
Indication 0 ∠°:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Check voltage supply of throttle valve control unit and wiring to engine control unit → .
If the voltage supply and wiring are OK:
–  Renew engine control unit → Chapter
Continuation of checking in case of indication of more than 100 ∠°:
  N24-0303
–  Remove connector -1- off throttle valve control unit -2-.
Indication 0 ∠°:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Replace throttle valve control unit → Item.
Indication of over 100 ∠°:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Check voltage supply of throttle valve control unit and wiring to engine control unit → .
If the voltage supply and wiring are OK:
–  Renew engine control unit → Chapter
Checking voltage supply and wiring to control unit
–  Remove air filter → Fig..
  N24-0299
–  Remove connector -1- off throttle valve control unit -2-.
–  Connect the multimeter to measure voltage to contacts 4+7 of the connector.
–  Switch ignition on.
   Specification: 4.5 V min
–  Switch ignition off.
–  Connect multimeter to measure voltage at connector contacts 3+7.
–  Switch ignition on.
   Specification: 9 V min
–  Switch ignition off.
  N24-0304
–  Connect test box -V.A.G 1598/18- to control unit wiring harness.
  N24-0334
–  Check wiring for open circuit between test box and connector using current flow diagram.
  N24-0170
ContactTest box -V.A.G 1598/18-, socket
12
226
310
414
541
717
816
Wire resistance: 1,5 Ω max.

–  Also check wires for short circuits to one another.
   Specification: ∞ Ω
If no wiring fault is detected:
–  Check engine control unit voltage supply → Chapter.
   

Intake manifold pressure sender: checking > < Engine operating conditions: checking