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Testing throttle valve actuator sensor > < Testing idling switch

A4 Mk1

Motronic Fuel Injection and ignition system (4-cyl.) 07.96ä
Checking 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 =>Page01-58
 
→ Indicated on display:
Read measurement block 1    ⇒
    0 rpm        0.00 ms        4 -5        12.05 before TDC
  • ‒ Check display in display zone 3.
 
→ Specified value: 0...5 <°
Read measurement block 1    ⇒
    0 rpm        0.00 ms        4 -5        12.05 before TDC
  • ‒ Slowly floor accelerator pedal.
 
→ Specified value: The readout in display zone 3 should increase steadily until it reaches 85 - 90 <° (with accelerator pedal fully depressed).
Read measurement block 1    ⇒
    0 rpm        0.00 ms        86 -5      12.0o before TDC

If either the initial or the final specification is not achieved:

  • ‒ Check accelerator cable setting

=> Engine mechanics; Repair group 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 (voltage measurement range) to contact 4 on the connector and to earth.
  • ‒ Switch the ignition on.
  • Specification: approx. 5 V
  • ‒ Connect test box V.A.G 1598/22 to wiring harness for engine control unit
    .

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

62

5

75

7

67
  • ‒ Rectify any open/short circuit as necessary.

If no wiring fault is detected:

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

Testing throttle valve actuator sensor > < Testing idling switch