Volkswagen Workshop Service and Repair Manuals

Special tools, testers and auxiliary items

• ◆ Fault reader V.A.G 1551 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

Test conditions

• ● After switching ignition on do not operate starter.

Test sequence

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

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

• ‒ Input 02 for "Display group number" and confirm with Q.

Note:

If something different is indicated on the display:

=> Fault reader operating instructions

• ‒ Note injection period in display zone 2.
• ‒ Operate starter. The injection timing display must change.

Note:

If the fault reader display is terminated when operating the starter, the cause is a too low operating voltage for the fault reader during starting. In this case the vehicle battery must be recharged.

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

If injection timing display does not change:

• ‒ → Detach 3 pin connector to sender -1-.
• ‒ Check voltage between contacts 1+3 of detached connector.
       Specification: Min. 9 V
• ‒ Switch off ignition

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.
• ‒ Check wiring between test box and 3 pin connector for open circuit according to current flow diagram.
       Contact 1+socket 68
       Contact 2+socket 67
       Contact 3+socket 33
       Wire resistance: Max. 1.5 ω
• ‒ Additionally check wires for short to one another.
       Specification: ∞ω

If no wiring fault is detected and voltage was present between contacts 1+3:

• ‒ Replace engine speed sender (G28).

If no wiring fault is detected and no voltage was present between contacts 1+3:

• ‒ Renew Digifant control unit (J169)
  , item 11 .