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Testing the speed signal > < Inspecting throttle valve control unit

Octavia Mk1

Check intake manifold pressure sender
Check intake manifold pressure sender
Special tools and workshop equipment required
t  Vehicle system tester -V.A.G 1552 - with cable -V.A.G 1551/3-
t  Hand-held multimeter -V.A.G 1526 A- or multimeter -V.A.G 1715-
t  Test box -V.A.G 1598/22-
t  Measuring tool set -V.A.G 1594 A -
t  Current flow diagram
Test sequence
–  Connect vehicle system tester and select engine electronics control unit with the address word 01. The engine must be idling for this step. (Connecting up the vehicle system tester and selecting the engine electronics control unit → Chapter).
   
Read-out on display:
–  Enter 08 for the function “Read measured value block” and confirm the entry with Q.
  
Vehicle system test               HELP
Select function XX
Read-out on display:
–  Enter 03 and confirm entry with the Q key.
  
Read measured value block     HELP
Enter display group number XX
Read-out on display: (1 to 4 = display fields)
–  Read off read-out for engine load in display field 2 and note down this value.
–  Briefly open throttle valve. Thus, the value for the engine load must increase briefly.
The read-out stays at a constant 0% or 100%.
  
Reading measured value block 3     ->
       1          2          3         4
DisplayCauseContinue test
0 %Line interruption or short-circuit to earth → Anchor
100 %Short circuit to positive → Anchor

Continuation of the test if the read-out is 0%:
   
–  Disconnect plug -1- from intake manifold pressure sender -G71- with intake air temperature sender -G42--2- (engine stalls).
–  Bridge contacts 3+4 at plug.
Read-out: 100%:
–  Press → key.
–  Enter 06 for the function “End output” and confirm with key Q.
–  Switch off ignition.
–  Replace intake manifold pressure sender -G71- with intake air temperature sender -G42--2- → Anchor, position 1.
Read-out: 0 %:
–  Press → key.
–  Enter 06 for the function “End output” and confirm with key Q.
–  Switch off ignition.
  N24-0306
–  Connect test box -V.A.G 1598/22 - at wiring loom to the 1AV control unit.
–  Check wiring between the test box and the plug for open circuit according to the current flow diagram.
   Contact 3+bush 62
   Contact 4+bush 61
   Cable resistance: max. 1.5 Ω
–  Also test wire contact 4 for short-circuit to earth and to contact 1.
   Specified value: ∞ Ω
If the lines are not found to be faulty:
–  Replace 1AV control unit -J382- → Item.
Continuation of the test if the read-out is 100 %:
  S24-0104
–  Disconnect plug -1- from intake manifold pressure sender -G71- with intake air temperature sender -G42--2- (engine stalls).
Read-out: 0 %:
–  Press → key.
–  Enter 06 for the function “End output” and confirm with key Q.
–  Switch off ignition.
–  Replace intake manifold pressure sender -G71- with intake air temperature sender -G42--2- → Anchor, position 1.
Read-out: 100 %:
–  Press → key.
–  Enter 06 for the function “End output” and confirm with key Q.
–  Switch off ignition.
–  Disconnect plug from 1AV control unit.
–  Check the wiring to the 1AV control unit connector on the 4-pin plug contact 4 for short-circuit to wire contact 3 as well as to battery positive.
   Specified value: ∞ Ω
If the lines are not found to be faulty:
–  Replace 1AV control unit -J382- → Item.
  N24-0305

Testing the speed signal > < Inspecting throttle valve control unit