Volkswagen Workshop Service and Repair Manuals

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electornics control unit (address word 01). Carry out selection at idling.

• ‒ Input 08 for "Read measured value block" function and confirm with Q.

• ‒ Input 03 for "display group number " and confirm with Q.

Note:

If something different is indicated on the display:

=> Fault reader operating instructions.

• ‒ Read-off throttle valve angle in diplay zone 3.
       Specification: 2.5...6.5 <°.
• ‒ Slowly open throttle valve and watch angle display in display zone 3
  The figure must increase uniformly over the complete range.
• ‒ Press ⇒key.
• ‒ Input 06 for "End output" and confirm with Q.
• ‒ Switch off ignition

Note:

The display figure is dependent on the tolerance of the throttle valve potentiometer and does not correspond to the actual opening angle.

The maximum permissible displayed figure si ± 86<° .

If the figure does not increase uniformly:

• ‒ Replace throttle valve control part (J338).

If the display shows constant 2 <°:

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.
• ‒ Switch on ignition.
• ‒ Check wire for short to positive, to do this connect multimeter to measure voltage at test box sockets 1+41, no voltage if voltage present.
• ‒ Switch off ignition

Continuation if voltage is present:

If voltage of about 5V was present:

• ‒ → Separate 8 pin connector to throttle valve control part.
• ‒ Switch on ignition.
• ‒ Check wiring at 8 pin connector contacts 4+5 for short to one another according to current flow diagram.:

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

• ‒ → Separate 8 pin connector to throttle valve control part.
• ‒ Check wiring between test box and 8 pin connector for open circuit according to current flow diagram.
       Contact 5 + socket 41
       Wire resistance: max. 1.5ω

If no wiring fault is detected:

• ‒ Replace throttle valve control part (J338).