Volkswagen Workshop Service and Repair Manuals

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with cable V.A.G 1551/3
• ◆ Adapter set V.A.G 1594
• ◆ Test box V.A.G 1598/31
• ◆ Current flow diagram

Check conditions

• ● → Fuses 13 and 36 must be OK.
• ● Earth connection in plenum chamber OK.
• ● The battery voltage must be at least 11.5 V.
• ● All electrical consumers, e.g. lights and rear window heating must be switched off.
• ● If the vehicle is equipped with an air conditioning system, this must be switched off.
• ● Alternator OK, checking:

=> Current flow diagrams, Electrical fault finding and Fitting locations

Test sequence

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552). Start engine and select "Address word" 01 of engine control unit. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine control unit .)

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

• ‒ Press keys 0, 0 and 4 for "Display group number 4" and confirm entry with Q key.

• ‒ Read off figure displayed in display zone 2.
       Specification: At least 11.5 V
• ‒ Press the ⇒key.
• ‒ Press keys 0 and 6 for the "End output" function and confirm input with the Q key.

• ‒ Switch off ignition.

If the specification is not attained:

• ‒ → Connect test box V.A.G 1598/31 to control unit wiring harness. The engine control unit remains disconnected.

Checking voltage supply terminal 30

• ‒ Measure voltage supply with multimeter and aux. cables from V.A.G 1594 between test box sockets 1 + 62 and 2 + 62:
       Specification: min. 11.5 V

If the specification is not attained:

• ‒ Check wiring to fuse carrier and earth connection of engine control unit using current flow diagram:

=> Current flow diagrams, Electrical fault finding and Fitting locations

Checking voltage supply terminal 15

• ‒ Measure voltage supply with multimeter and aux. cables from V.A.G 1594 between test box sockets 1 + 3 and 2 + 3:
• ‒ Switch on ignition.
       Specification: min. 11.5 V

If the specification is not attained:

• ‒ Check wiring to fuse carrier and earth connection of engine control unit using current flow diagram:

=> Current flow diagrams, Electrical fault finding and Fitting locations