Checking ECM Voltage Supply

CHECKING ECM VOLTAGE SUPPLY
NOTE:
To check the ECM voltage supply also refer to On-Board Diagnostics, "Read Measuring Value Block" function 08, display group 001, display field 4.

REQUIREMENTS
^ Circuit breaker -S64- must be OK (yellow holder in electronic box in passenger side footwell).

TEST PROCEDURE
- Connect VAG 1598 test box with VAG 1598/12 adapter harness to ECM wiring harness. Connecting VAG 1598/31 Test Box
^ Adapter harness is not connected to ECM.
- Switch ignition on.
- Connect US 1115 LED Tester or equivalent between test box socket 8 (B+ via ignition) and Ground (GND).
^ LED must light up

If LED does NOT light up:
- Check for break in wiring according to wiring diagram and repair if necessary.
- Connect LED Tester to test box socket 8 (B+ supply via ignition) and successively to sockets 1,2,3 and 16 (Ground connections).
^ LED must light up in each case

If LED does not light up:
- Check wiring between intake manifold GND point and connector -D- using wiring diagram.

ECM Harness Connectors:

Test box socket ECM connector D
terminal
1 1
2 2
3 3
16 16

- Switch ignition off.
- Connect VAG 1598 test box with VAG 1598/11 adapter harness to ECM wiring harness.
^ Adapter harness is not connected to ECM.
- Connect VAG 15278 voltage tester between test box socket 40 (permanent 8+) and Ground (GND).
^ LED must light up.

If LED does NOT light up:
- Check wiring connection between ECM connector -8- terminal 20 and central electric panel according to wiring diagram.