Volkswagen Workshop Service and Repair Manuals

Components of the throttle valve control part (J338):
Throttle valve drive (G186), throttle valve drive angle sender (G187), throttle valve potentiometer (G69) and idling switch (F60)

Note:

If the throttle valve control part is replaced, the new control part must without fail be adapted to the engine control unit .

On vehicles fitted with an automatic gearbox the gearbox control unit must also be adapted:

=> Self-diagnosis for automatic gearbox 01M; Repair group 01; Performing self-diagnosis; Initiating basic setting

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ 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 1598/22
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Adapter set V.A.G 1594
• ◆ Current flow diagram

Test conditions

• ● Throttle valve not damaged or dirty.
• ● Throttle cable adjustment OK, checking:

=> Repair group 20; Removing and installing parts of fuel supply system; Adjusting throttle mechanism

Checking idling switch (F60)

• ‒ Connect the fault reader V.A.G 1551 (V.A.G 1552). Then switch ignition on and select engine control unit with the "Address word" 01.
  (Connecting fault reader and selecting engine control unit => Page 01-8 .)

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

• ‒ Press keys 0, 5 and 4 for "Display group number 54" and confirm entry with Q key.

• ‒ Check the operating mode display in display zone 2.
       Display: Idling
• ‒ Slowly open throttle valve. After free travel, a stop is reached when opening throttle valve further the 4th position from left must jump to part throttle
       Display: Part throttle

Display constantly remains on one operating condition:

Continuation of check when display shows part throttle

• ‒ → Pull 8 pin connector off throttle valve control part.
• ‒ Bridge connector contacts 3+7 with aux. cables from V.A.G 1594 and observe display.

If display jumps to idling:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Replace throttle valve control part (J338).

If display remains on idling:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Check voltage supply of throttle valve control part and wiring to control unit => Page 24-51 .

If the voltage supply and wiring is OK:

• ‒ Renew engine control unit => Page 24-120 .

Continuation of check when display constantly shows idling

• ‒ → Pull 8 pin connector off throttle valve control part.

If display jumps to part throttle:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Replace throttle valve control part (J338).

If display remains on part throttle:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Check voltage supply of throttle valve control part and wiring to control unit => Page 24-51 .

If the voltage supply and wiring is OK:

• ‒ Renew engine control unit => Page 24-120 .

Checking throttle valve drive (G186) and throttle valve drive angle sender (G187)

Test conditions

• ● Coolant temperature must be at least 85 °C, =>display group 04, display zone 3.

Test sequence

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552). Start engine and select "Address word" 01 of engine control unit. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine control unit => Page 01-8 .)

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

• ‒ Press keys 0, 6 and 0 for the "Display group number 60" and confirm entry with Q key.

• ‒ Check the operating mode in display zone 3
       Display: Idling speed
• ‒ Check throttle valve angle at idling stop in display zone 1
       Specification: 1...5 <°
• ‒ Check throttle valve positioner at idling stop in display zone 2.
       Specification: 60...90 %

If the specifications are not attained:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.

• ‒ Switch off ignition.
• ‒ → Pull 8 pin connector off throttle valve control part.
• ‒ Measure resistance of throttle valve positioner between following contacts:
       Contact 1 + 2
       Specification: 1...5 ω

If the specification is not obtained:

• ‒ Replace throttle valve control part (J338).

If the specification is obtained:

• ‒ Check voltage supply of throttle valve control part and wiring to control unit => Page 24-51 .

Checking throttle valve potentiometer (G69)

Test sequence

• ‒ Connect the fault reader V.A.G 1551 (V.A.G 1552). Then switch ignition on and select engine control unit with the "Address word" 01.
  (Connecting fault reader and selecting engine control unit => Page 01-8 .)

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

• ‒ Press keys 0, 5 and 4 for "Display group number 54" and confirm entry with Q key.

• ‒ Read off throttle valve angle in display zone 3.
       Throttle valve in start position: 1...5 <°
• ‒ Slowly open throttle valve slowly until fully open and observe angle display in display zone 3. The figure must increase uniformly over
  the complete range
       up to a min. 75 <°.
• ‒ 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.

If the figure does not increase uniformly:

• ‒ Replace throttle valve control part (J338).

If the display constantly shows 0 <° or is above 90 <°:

Continuation of check when display 0 <°:

• ‒ → Pull 8 pin connector off throttle valve control part.
• ‒ Bridge connector contacts 5+7 with auxiliary cables from V.A.G 1594 and observe display.

If display jumps above 90 <°:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Replace throttle valve control part (J338).

If display remains at 0 <°:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Check voltage supply of throttle valve control part and wiring to control unit => Page 24-51 .

If the voltage supply and wiring is OK:

• ‒ Renew engine control unit => Page 24-120 .

Continuation of check when display is above 90 <°:

• ‒ → Pull 8 pin connector off throttle valve control part.

If display jumps to 0 <°:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Replace throttle valve control part (J338).

If display remains above 90 <°:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Check voltage supply of throttle valve control part and wiring to control unit => Page 24-51 .

If the voltage supply and wiring is OK:

• ‒ Renew engine control unit => Page 24-120 .

Checking voltage supply and wiring to control unit

• ‒ → Pull 8 pin connector off throttle valve control part.
• ‒ Connect multimeter to measure voltage at connector contacts 4+7.
• ‒ Switch on ignition.
       Specification: min. 4.5 V
• ‒ Connect multimeter to measure voltage at connector contacts 3+7.
       Specification: at least 9 V

• ‒ Switch off ignition.

If the specifications are not attained:

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

• ‒ → Check wiring for open circuit between test box and connector using current flow diagram:
       Contact 1+socket 66
       Contact 2+socket 59
       Contact 3+socket 69
       Contact 4+socket 62
       Contact 5+socket 75
       Contact 7+socket 67
       Contact 8+socket 74
       Wire resistance: max. 1.5 ω
• ‒ Additionally check wires for short to one another.
       Specification: ∞ω

If no fault is detected in the wiring:

• ‒ Check engine control unit voltage supply => Page 24-115 .