Component Tests and General Diagnostics

Control Module Voltage Supply, Check

Special tools and equipment
- VAG1551 scan tool or VAG1552 mobile scan tool with VAG1551/3B cable
- VAG1598/31 test box
- VAG1526 hand multimeter or VAG1715 multimeter
- VAG1594 adapter set
- Wiring diagram

Check conditions
- The battery voltage must be at least 11.5 V.







- All fuses must be OK.
- Alternator OK, checking.

Test sequence
- Connect VAG1551 scan tool (VAG1552). Start engine and select "Address word" 01 of engine control module. Engine must be running at idling speed. (Connecting scan tool and selecting engine control module). Refer to "VAG1551 Scan Tool Tools and Equipment

Indicated on display:


Rapid data transfer HELP
Select function XX


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

Indicated on display


Read measured value block HELP
Input display group number XXX


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

Indicated on display: (1 to 4 = Display zones)


Read measured value block 4 ->
1 2 3 4


- Read off figure displayed in display zone 2.
Specification: At least 11.5 V
- Press -> key.
- Press keys 0 and 6 for "End data transfer" function and confirm input with Q key.
- Switch ignition off.

If the specification is not attained:







- Connect VAG1598/31 test box to control module wiring harness. Engine control module remains disconnected.

Checking voltage supply terminal 30
- Measure supply voltage between test box sockets 1+62 using multimeter and adapter cables from VAG1594:
Specification: at least 11.5 V

If the specification is not attained:
- Check wiring connections to relay plate according to wiring diagram.

Checking voltage supply terminal 15
- Measure supply voltage with multimeter and aux. cables from VAG1594 between test box sockets 2 and 3:
- Switch ignition on.
Specification: min. 11.5 V

If the specification is not attained:
- Check wiring connections to relay plate according to wiring diagram.