Audi Workshop Service and Repair Manuals

The throttle valve actuator angle senders G187 and G188 signal the position of the throttle valve to the engine control unit. Both angle senders are located in the throttle valve control part.

• ‒ Connect the vehicle diagnostic, testing and information system VAS 5051 or fault reader V.A.G 1551 and select the engine electronics control unit with "address word" 01 .
  For this purpose, the ignition must be switched on.

• ‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

• ‒ Press keys 0, 6 and 2 for "display group number 62" and confirm entry with Q key.

• ‒ Check specifications for electronic throttle potentiometer voltages.

Note:

The engine control unit converts and displays the voltage readings from the angle senders as percentages of 5 V. (A 5 Volt supply corresponds to 100 %).

• ‒ Observe readouts in display zones 1 and 2.
• ‒ Slowly depress accelerator pedal.

Percentage displayed in zone 1 should rise evenly. The tolerance range from 3...93 % is not fully utilised.

Percentage displayed in zone 2 should fall evenly. The tolerance range from 97...3 % is not fully utilised.

If the displays are not as described:

• ‒ Check voltage supply and wiring of throttle valve control part => Page 24-160.

Pay particular attention to connectors, which may be loose, not properly engaged or corroded.

=> Current Flow Diagrams, Electrical Fault-Finding and Fitting Locations

• ‒ Check the accelerator position senders
  => Page 24-162.

Notes:

• ◆ The reason why the value in display zone 1 rises and that in zone 2 falls is that the potentiometers (angle senders) in the throttle valve control part operate in opposite directions.
• ◆ This means that the voltage picked off by one of the angle senders runs in the direction of 5 V. (As the throttle is opened, the voltage becomes greater and the percentage increases).
• ◆ The voltage picked off by the angle sender 2 runs from 5 V in the direction of 0 V. (As the throttle is opened, the voltage becomes smaller and the percentage decreases).

Checking the voltage supply to the throttle valve control part.

• ‒ Unplug the connector from the throttle valve control part.
• ‒ Switch the ignition on.
• ‒ → Connect hand-held multimeter (voltage range) between the following contacts on the connector:

If specifications are not attained, also check the signal and activation lines of the throttle valve actuator => Page 24-161.

If specifications are not attained:

Check wiring between engine control unit and throttle valve control part
=> Page 24-161.

Checking wiring

• ‒ → Unplug the connector from the throttle valve control part.
• ‒ Connect the V.A.G 1598/31 test box to wiring harness leading to engine control unit; the engine control unit should not be connected.
  => Page 24-23.

The following wiring connections are to be checked for open circuits and/or short to positive or negative.

• ‒ Rectify any open/short circuit as necessary.

If no wiring fault is detected:

• ‒ Replace throttle valve control part.