Audi Workshop Service and Repair Manuals

Special tools, workshop equipment, test and measuring appliances and auxiliary items required

• ◆ V.A.G 1526 Hand multimeter
• ◆ V.A.G 1594 A Adapter set
• ◆ V.A.G 1598/22 Test box
• ◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3A
• ◆ Current flow diagram

Function

Both accelerator pedal position senders -G79- and -G185- on the accelerator pedal pass the driver's requirements on to the engine control unit independently of one another. Both senders are installed together in a housing.

Check conditions

• ● → The fuses must be OK.
• ● The battery voltage must be at least 11.5 V.
• ● All electrical consumers, e.g. lights and rear window heating must be switched off.
• ● If the vehicle is equipped with an air conditioning system, this must be switched off.

Test sequence

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and with ignition switched on select engine electronics control unit with the "Address word" 01:

=> Repair group 01; General notes on self-diagnosis; Connecting fault reader V.A.G 1551 and selecting engine control unit

• ‒ 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 the "Display group number 62" and confirm entry with Q key.

• ‒ Check specifications of sender 1 (G79) at idling stop in display zone 3.
      Specification: 12...97 %
• ‒ Check specifications of sender 2 (G185) at idling stop in display zone 4.
      Specification: 4...49 %

Note:

The engine control unit calculates the voltage values of the angle sender in percent relative to 5 Volt and displays these as a percentage figure (5 Volt supply voltage equates to 100 %).

• ‒ Operate the accelerator pedal slowly until fully depressed and observe the angle sender figures in display zones 3 and 4:

• The percent figures in display zone 3 must rise evenly. The tolerance range of 12...97 % is not covered completely.
• The percent figures in display zone 4 must rise evenly. The tolerance range of 4...49 % is not covered completely.

Note:

The figure displayed in display zone 3 must always be approximately double that displayed in display zone 4.

• ‒ Press the ⇒key.
• ‒ Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.
• ‒ Switch off ignition.

If the display does not indicate as described:

• ‒ Check accelerator pedal position sender voltage supply and wiring connections .

Checking voltage supply and wiring to control unit

• ‒ Remove cover in footwell (driver's side).
• ‒ Pull 6-pin connector off accelerator pedal position sender.
• ‒ Switch ignition on.
• ‒ → Connect multimeter to measure voltage at the following contacts of the connector:
      Contact 1 + earth
      Contact 1 + 5
      Contact 2 + earth
      Contact 2 + 3
      Specification: minimum 4.5 V
• ‒ Switch off ignition.

If the specifications are not obtained:

• ‒ Remove wiper arms and cowl panel:

=> Electrical system; Repair group 92; windscreen wiper system; removing and installing windscreen wiper system

• ‒ → Connect test box V.A.G 1598/22 to control unit wiring harness.

• ‒ → Check wiring for open circuit between test box and 6-pin connector (connector to control unit) using current flow diagram.
      Contact 1+socket 6
      Contact 2+socket 8
      Contact 3+socket 7
      Contact 4+socket 33
      Contact 5+socket 19
      Contact 6+socket 45
      Wire resistance: Max. 1.5 ω
• ‒ Additionally check wires for short to one another, to vehicle earth and to battery positive.
      Specification: ∞ω

If no fault is detected in the wiring:

• ‒ Renew accelerator pedal position sender
  , item 4
• ‒ Interrogating and erasing fault memory:

=> Repair group 01; Fault memory; Interrogating and erasing fault memory of engine control unit