Volkswagen Workshop Service and Repair Manuals

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
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Test box V.A.G 1598/18
• ◆ Adapter set V.A.G 1594
• ◆ Current flow diagram

Notes:

• ◆ The adjustment is only necessary if the throttle valve positioner or the injection unit lower part is replaced.
• ◆ The idling switch (F60) can only be adjusted if the throttle valve positioner is fully out.

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01); carry out selection with ignition switched on.
  

• ‒ Input 04 for "Initiate basic setting" and confirm with Q.

• ‒ Input 01 for "Display group number" and confirm with Q.

Checking function

• ‒ Observe 2nd position from left in display zone 4 -8 digit number block-.
       Specification: 01000010
• ‒ Open throttle valve slightly. The display at 2nd position from left must jump to 0
       Display: 00000010

If the specifications are not attained:

• ‒ Remove air cleaner.

Continuation of check when display = always 1:

• ‒ → Pull plug -1- off throttle valve positioner (V60) -2- .

Display 0:

• ‒ Replace throttle valve positioner (V60).

Display 1:

• ‒ Press ⇒ key.
• ‒ Input 06 for "End output" and confirm with Q.
• ‒ Switch off ignition
• ‒ Pull connector off Mono Motronic control unit.
• ‒ Check wiring to control unit at 6 pin connector contact 5 for short to wire contact 4 and to vehicle earth.

If no fault in wire is detected:

• ‒ Renew Mono Motronic control unit (J257)
  , item 10 .

Continuation of check when display = always 0:

• ‒ → Pull plug -1- off throttle valve positioner (V60) -2- .
• ‒ Bridge connector contacts 4+5 with aux. cables from V.A.G 1594 and observe display.

Display 1:

• ‒ Replace throttle valve positioner (V60).

Display 0:

• ‒ Press ⇒ key.
• ‒ Input 06 for "End output" and confirm with Q.
• ‒ Switch off ignition

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.
• ‒ Check wiring between test box and 6 pin connector for open circuit according to current flow diagram.
       Contact 4+socket 20
       Contact 5+socket 10
       Wire resistance: Max. 1.5 ω

If no wiring fault is detected:

• ‒ Renew Mono Motronic control unit (J257)
  , item 10 .

Checking adjustment

Note:

The adjustment of the idling switch must be performed in function "04 Basic setting" -positioner fully extended-. If the basic setting has to be exited for checking the wiring, the system must be brought back to basic setting with ignition switched on.

• ‒ Select display group 00, to do this
• ‒ On V.A.G 1551 press key 1
• ‒ On V.A.G 1552 press key ↓

• ‒ Observe displayed figure in display zone 2 (throttle valve potentiometer path 1):
       Specification: 196...200

If the specification is not obtained:

• ‒ Remove air cleaner.

• ‒ → Correct adjustment on the stop screw-arrow-.
       Setting value: 198±1

Note:

If during adjustment the throttle valve is opened to gain access to the screw, the control unit will move the throttle valve positioner back. To move the positioner fully out again, the function basic setting must be selected again.

• ‒ Press ⇒ button. The throttle valve positioner must move in to its start point.
• ‒ Input 06 for "End output" and confirm with Q.

If it is not possible to adjust to specification:

• ‒ Renew injection unit lower part.