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 with the "Address word" 01. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine electronics control unit .)

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

• ‒ Press keys 0 and 2 for "Display group number 02" and confirm entry with Q key.

• ‒ Read off figure displayed in display zone 3.
       Specification: approx. battery voltage constant
• ‒ Press ⇒key.

• ‒ Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.

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 ignition on.
• ‒ Check supply voltage with multimeter and aux. cables from V.A.G 1594 between the test box sockets 1+8:
       Specification: Min. 9 V
• ‒ Check voltage with multimeter and aux. cables from V.A.G 1594 between test box sockets 1+23:
       Specification: Min. 11 V

If the specifications are not attained:

• ‒ Replace voltage supply relay (J363).

Checking voltage supply terminal 15

Test conditions

• ● Fuse 15 OK

• ‒ Check voltage supply with multimeter and aux. cables from V.A.G 1594 between test box sockets 1+38:
       Specification: Min. 11 V

If the specification is not obtained:

• ‒ Check wiring according to current flow diagram.