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Testing throttle valve actuator sensor > < Testing idling switch

A4 Mk1

Motronic fuel injection and ignition system (4-cyl.turbo) > 07.96
Testing throttle valve control unit
Testing throttle valve potentiometer

The throttle valve potentiometer (G69) informs the engine control unit of the position of the throttle valve.

  • ‒ Read measured value block, Display Group 01, engine stopped =>Page 01-49
 
→ Indicated on display:
Read measured value block 1    ⇒
    0.rpm        0.00 ms    4 -5    12.0 5before TDC
  • ‒ Check readout in display zone 3.
 
→ Specified result: 0...5 <°
Read measured value block 1    ⇒
    0 rpm        0.00 ms    4 -5    12.0 5before TDC
  • ‒ Slowly depress accelerator pedal.
 
→ Specified result: The readout in display zone 3 should increase steadily until it reaches 85...90 <° (with accelerator pedal fully depressed).
Read measured value block 1    ⇒
    0 rpm        0.00 ms    86 -5    12.0 5before TDC

If either the initial or final specified result is not achieved:

  • ‒ Check accelerator cable setting.

=> Engine mechanics; Rep.-Gr. 20;

If the display does not change or only changes irregularly:

  • ‒ Switch off ignition.
 
A23-0006
  • ‒ → Disconnect the connector from the throttle valve control unit.
  • ‒ Connect the multimeter for voltage measurement to contact 4 on the connector and to earth.
  • ‒ Switch the ignition on.
  • Specified result: approx. 5 V.
  • ‒ Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit.
    =>Page 24-6.

The following wiring connections should be checked for open circuits and/or short to positive or negative.
 
A23-0006

8-pin connector on the wiring harness, contact.

Test box V.A.G 1598/22, socket.

4

11

5

75

7

67
  • ‒ Rectify short circuit or open circuit if necessary.

If no fault is detected in the wiring:

  • ‒ Renew the throttle valve control unit (J338).

Testing throttle valve actuator sensor > < Testing idling switch