Component Tests and General Diagnostics
Voltage supply for control module, checking
Special tools and equipment
- V.A.G 1551 scan tool (or VAG 1552 mobile scan tool) with VAG 1551/3B cable
- VAG 1598/31 adapter cable
- VAG 1526 multimeter or VAG 1715 multi meter
- VAG 1594 connector test kit
- Wiring diagram
Test requirements
- Battery voltage must be at least 11.5 volts.
- Fuses no. 7 and 29 must be OK.
- Generator (GEN) must be OK, checking:
Test sequence
- Connect V.A.G 1551 scan tool (VAG 1552). Start engine and select the Engine Control Module (ECM) using address word 01. (connecting scan tool and selecting ECM). Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1551 Scan Tool", Testing and Inspection
Indicated on display:
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read measuring value block" function 08. Press -Q- button to confirm input.
Indicated on display:
Read measuring value block HELP
Enter display group number XXX
- Press buttons -0-, -0- and -4- to select "Display group number 4". Press -Q- button to confirm input.
Indicated on display: (1 to 4 - display fields)
Read measuring value block 4 ->
1 2 3 4
- Read value indicated in display field 2. Specification: at least 11.5 V
- Press -> button.
- Press buttons -0- and -6- to select "End data transfer" function 06. Press -Q- button to confirm input.
- Switch ignition off.
If specified value is not obtained:
- Connect VAG 1598/31 adapter cable to control module wiring harness. Engine Control Module (ECM) is not connected.
Checking voltage supply at terminal 30
- Use multimeter and adapter cables from VAG 1594 connector test kit to measure supply voltage between sockets 1 + 62 of test box: Specification: at least 11.5 V
If specified value is not obtained:
- Check wire connections to relay carrier according to wiring diagram:
Checking voltage supply at terminal 15
- Use multimeter and adapter cables from VAG 1594 connector test kit to measure supply voltage between sockets 2 + 3 of test box:
- Switch ignition on. Specification: at least 11.5 V
If specified value is not obtained:
- Check wire connections to relay carrier according to wiring diagram.
Check voltage supply via main relay
- Use multimeter and adapter cables from VAG 1594 connector test kit to measure supply voltage between sockets 2 + 121 of test box:
- Switch ignition on. Specification: at least 11.5 V
If specified value is not obtained:
- Check wire connections to relay carrier according to wiring diagram:
- Check activation wire from Engine Control Module (ECM) pin 21 to voltage supply relay for Motronic Engine Control Module (ECM) voltage supply relay -J271- according to wiring diagram.