Volkswagen Workshop Service and Repair Manuals

Note:

If the throttle valve control part J338 is removed and installed or replaced the basic setting must be performed .

Special tools, testers and auxiliary items

• ◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
• ◆ Test box V.A.G 1598/18
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Adapter set V.A.G 1594

• ◆ Current flow diagram

Checking voltage supply

• ‒ → Separate 8 pin connector to throttle valve control part (J338).
• ‒ Connect multimeter using aux. cables from V.A.G 1594 to measure voltage at contacts 3+7 of connector.
• ‒ Switch on ignition.
       Specification: 9.0...14.5 V

• ‒ Connect multimeter using aux. cables from V.A.G 1594 to measure voltage at contacts 4+7 of connector.
       Specification: 4.0...6.0 V
• ‒ Switch off ignition.

If the specifications are not attained:

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom -arrow-.

• ‒ → Check wiring between test box and 8 pin connector for open circuit according to current flow diagram.
       Contact 3+socket 10
       Contact 4+socket 41
       Contact 7+socket 33
       Wire resistance: Max. 1.5 ω
• ‒ Check wiring at 8 pin connector for short to one another.
       Contact 7+socket 10
       Contact 7+socket 41
       Contact 4+socket 33
       Specification: ∞ω
• ‒ Reconnect connector.

If no wiring fault is detected:

• ‒ Replace Motronic control unit (J220).
• ‒ Read-out the readiness code=> Page 01-35 .

Checking idling switch

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address word" 01. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine electronics control unit => Page 01-6 .)

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

• ‒ Press keys 0, 0 and 5 for "Display group number 5" and confirm entry with Q key.

• ‒ Check the idling switch (display zone 4):

Continuation

• ‒ Switch off ignition.
• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom -arrow-.
• ‒ With throttle valve closed connect multimeter to measure resistance at test box sockets 10+33.
       Specification: max. 5.0 ω
• ‒ Slowly open throttle valve.
       Specification: ∞ω

If the specifications are not obtained:

• ‒ → Separate 8 pin connector to throttle valve control part (J338).
• ‒ Check wiring between test box and 8 pin connector for open circuit according to current flow diagram.
       Contact 3+socket 10
       Contact 7+socket 33
       Wire resistance: Max. 1.5 ω
• ‒ Check wiring at 8 pin connector for short to one another.
       Contact 7+socket 10
       Specification: ∞ω
• ‒ Reconnect connector.

If no wiring fault is detected:

• ‒ Replace throttle valve control part (J338).
• ‒ Read-out the readiness code=> Page 01-35 .

Checking throttle valve positioner and throttle valve positioner potentiometer

Test conditions

• ● Coolant temperature at least 80 °C

Test sequence

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address word" 01. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine electronics control unit => Page 01-6 .)

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

• ‒ Press keys 0, 3 and 7 for "Display group number 37" and confirm entry with Q key.

• ‒ Check the specifications for the idling control(display zone 1...4):

     1)     Up-to-date specifications:

=> Exhaust emissions test binder

• ‒ Press C key.
• ‒ Press keys 0, 3 and 6 for "Display group number 36" and confirm entry with Q key.

• ‒ Check the specifications for the idling control(display zone 2 + 3):

1)     On vehicles with manual gearbox '0' is always displayed.

Evaluating display group 37

1)     Value remains constant also at longer idling phase.

Evaluating display group 36

Continuation

• ‒ Switch off ignition.
• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom -arrow-.
• ‒ Switch ignition on.
• ‒ With throttle valve closed connect multimeter to measure resistance at test box sockets 27+53.
       Specification: 3...200 ω

If the specification is not obtained:

• ‒ → Separate 8 pin connector to throttle valve control part (J338).
• ‒ Repeat resistance measurements of throttle valve control part at contacts 1 + 2,
       Specification: 3...200 ω

If the specifications are again not attained:

• ‒ Replace throttle valve control part (J338).

If the specification is attained:

• ‒ Check wiring between test box and 8 pin connector for open circuit according to current flow diagram.
       Contact 1+socket 27
       Contact 2+socket 53
       Contact 7+socket 33
       Contact 8+socket 62
       Wire resistance: Max. 1.5 ω
• ‒ Check wiring at 8 pin connector for short to one another according to current flow diagram
       Contact 1+socket 53
       Contact 1+socket 62
       Contact 1+socket 33
       Contact 2+socket 33
       Contact 2+socket 62
       Contact 7+socket 62
       Specification: ∞ω
• ‒ Read-out the readiness code=> Page 01-35 .

Checking throttle valve potentiometer

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address word" 01. When doing this the ignition must be switched on but engine not running.
  (Connecting fault reader and selecting engine electronics control unit => Page 01-6 .)

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

• ‒ Press keys 0, 0 and 3 for "Display group number 3" and confirm entry with Q key.

• ‒ Check the throttle valve potentiometer specification (display zone 3):

• ‒ Slowly open throttle valve and watch angle display in display zone 3.
  The figure must increase uniformly over
       the complete range.
• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
• ‒ Switch off ignition.

Note:

The displayed figure is dependent on the tolerances of the throttle valve potentiometer and does not correspond to the actual opening angle. The maximum permissible displayed figure is 90.0 <°.

If the figure does not increase uniformly:

• ‒ Replace throttle valve control part (J338).
• ‒ Read-out the readiness code=> Page 01-35 .

Evaluating display group 3

Check wiring

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom -arrow-.
• ‒ Connect multimeter using aux. cables from V.A.G 1594 to measure resistance at test box sockets 01+40 and check wiring for short to earth.
       Specification: ∞ω
• ‒ Set multimeter to "Voltage measurement" range.
• ‒ Switch on ignition.
• ‒ Check wiring for short to positive
       if necessary note voltage value.
• ‒ Switch off ignition.

• ‒ → Separate 8 pin connector to throttle valve control part (J338).

Continuation if voltage is present:

If voltage of about 5 V was present:

• ‒ Connect multimeter using aux. cables from V.A.G 1594 to measure resistance at test box sockets 40+41 and check the wiring for short to one another.
       Specification: ∞ω

If the voltage was approx. battery voltage:

• ‒ Check wire at 8 pin connector contact 5 for short to battery positive according to current flow diagram.

Continuation if no voltage is present:

• ‒ Check wiring between test box and 8 pin connector for open circuit according to current flow diagram.
       Contact 5+socket 40
       Wire resistance: Max. 1.5 ω

If no wiring fault is detected:

• ‒ Replace throttle valve control part (J338).
• ‒ Read-out the readiness code=> Page 01-35 .