Audi Workshop Service and Repair Manuals

Special tools, testers and workshop equipment required

• ◆ V.A.G 1526 A
• ◆ V.A.G 1594 A
• ◆ V.A.G 1598/31
• ◆ VAS 5051 with VAS 5051/1

• or

• ◆ V.A.G 1551 with V.A.G 1551/3 A

Both accelerator pedal position sensors -G79 and -G185 are located on the accelerator pedal and completely independently signal the driver's requirements to the engine control unit. Both sensors are located in a housing.

Test sequence

• ‒ Connect up vehicle diagnosis, measurement and information system VAS 5051 or fault reader V.A.G 1551 and select engine electronics control unit with "Address word" 01 .
  When doing this the ignition must be switched on.

• ‒ Enter "08" to select the function "Reading measured value block" and confirm entry with Q key.

• ‒ Enter "062" to select "Display Group 062" and confirm entry with the Q key.

• ‒ Check specified values for electronic throttle potentiometer voltages.

Note:

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

• ‒ Observe readouts in display fields 3 and 4.
• ‒ Slowly depress accelerator pedal.

Percentage displayed in zone 3 should rise evenly. The tolerance range from 12...97% is not fully utilised.

Percentage displayed in zone 4 should also rise evenly. The tolerance range from 4...49% is not fully utilised.

Note:

The value displayed in zone 3 must always be about twice as large as that in zone 4.

If the displays are not as described:

• ‒ Check voltage supply and wiring for accelerator position sensor => Page 24-148.

Checking voltage supply for accelerator position sensors

• ‒ Remove driver's storage compartment.

=> General Body Repairs - Interior; Repair group 68; Dash panel; Removing driver's shelf

• ‒ Disconnect connector for accelerator position sensors.
• ‒ Switch on the ignition.

• ‒ → Connect multimeter as follows to measure voltage:

If the specified values are attained:

• ‒ Additionally check signal wires.

If the specified values are not attained:

• ‒ Check wiring between engine control unit and accelerator position sensors.

Checking wiring

• ‒ Connect the V.A.G 1598/31 test box to wiring harness leading to engine control unit; engine control unit should not be connected => Page 24-20.

• ‒ → Check for open circuit and short to positive or earth in the following wiring connections:

• ‒ Rectify any open/short as necessary.

If no wiring fault is detected:

• ‒ Replace accelerator position sensors.

=> Fuel supply petrol engines; Servicing throttle control