Volkswagen 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 1598/31 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.

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; Self-diagnosis; Connecting fault reader V.A.G 1551 and selecting engine electronics 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.

If the display does not indicate as described:

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

• ‒ Disconnect 6-pin connector for 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:

• ‒ → Connect test box V.A.G 1598/31 to control unit wiring harness. The engine control unit remains disconnected.
• ‒ Switch off ignition.

• ‒ → Check wiring between test box and connector for open circuit using current flow diagram.
       Contact 1+ socket 19
       Contact 2+ socket 18
       Contact 3+ socket 50
       Contact 4+ socket 51
       Contact 5+ socket 45
       Contact 6+ socket 64
       Wire resistance: max. 1.5 ω
• ‒ Additionally check the wiring for short to battery positive or earth.
• ‒ Additionally check wires for short to one another.

If no fault is detected in the wiring:

• ‒ Renew accelerator pedal position sender
  , item 3