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
• ◆ 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

Check conditions

• ● Battery voltage at least 11 V
• ● Alternator OK

Test sequence

Checking voltage supply via relay (J363)

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

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

• ‒ Input 02 for display group 02 and confirm with Q.

Note:

If something different is indicated on the display:

=> Fault reader operating instructions

• ‒ Read off figure displayed in display zone 3.
       Specification: approx. battery voltage constant
• ‒ Press ⇒ key.
• ‒ Input 06 for "End output" and confirm with Q.

If the displayed figure fluctuates or the battery voltage is not attained:

• ‒ Switch off ignition

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.
• ‒ Switch on ignition.
• ‒ Bridge sockets 1 and 9 with aux. cables from V.A.G 1594.
• ‒ Check voltage with multimeter and aux. cables from V.A.G 1594 between test box sockets 1+23:
       Specification: Min. 9 V

If the specifications are not attained:

• ‒ Replace voltage supply relay (J363).

Checking voltage supply terminal 30

• ‒ Check voltage supply with multimeter and aux. cables from V.A.G 1594 between test box sockets 1+54:
       Specification: Min. 9 V

If the specification is not obtained:

• ‒ Check wiring according to current flow diagram.

Checking voltage supply terminal 15

• ‒ Check voltage supply with multimeter and aux. cables from V.A.G 1594 between test box sockets 1+38:
       Specification: Min. 9 V

If the specification is not obtained:

• ‒ Check wiring according to current flow diagram.