Engine Control Module: Testing and Inspection

Voltage Supply For Control Module, Checking

Special tools and equipment
- VAG1551 scan tool (or VAG1552 mobile scan tool) with VAG1551/3B cable
- VAG1598/31 test box
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
- Wiring diagram

Test requirements







- All fuses must be OK.
- Battery voltage must be at least 11.5 volts.
- All electrical consumers like, for example, lights and rear window heating must be switched off.
- If vehicle is equipped with an A/C system, it must be switched off.
- Generator (GEN.) must be OK, checking:

Test sequence
- Connect VAG1551 scan tool (VAG1552). Start engine and select the Engine Control Module (ECM) using address word 01.

Connecting scan tool and selecting ECM. Refer to Scan Tool Connecting and Initial Checks. Scan Tool Testing and Procedures

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 0, 0 and 4 for the function "display group number 4", and then press Q to exit from input mode.

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

- Display Group 4 and its evaluation

If specified value is not obtained:
- Press the -> button.
- Press buttons -0- and -6- to select "End data transfer" function 06. Press -Q- button to confirm input.
- Switch ignition off.







- Connect VAG1598/31 test box to control module wiring harness. Engine Control Module (ECM) is not connected.

Checking voltage supply at terminal 30
- Use multimeter and adapter cables from VAG1594 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
- Switch ignition on.
- Use multimeter and adapter cables from VAG1594 connector test kit to measure supply voltage between sockets 2 + 3 of test box: Specification: at least 11.5V

If specified value is not obtained:
- Switch ignition off.
- Check wire connections to relay carrier according to wiring diagram:
- Check DTC memory, repair any malfunctions and then erase DTC memory.
- Read readiness code. If DTC memory was erased or Engine Control Module (ECM) was disconnected from continuous B+ supply, readiness code must be re-generated. Monitors, Trips, Drive Cycles and Readiness Codes Monitors, Trips, Drive Cycles and Readiness Codes