If EPC warning lamp does not illuminate

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Fig 1: Identifying Test Box V.A.G 1598/31 Connect To Control Module Wiring Harness

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Connect Adapter cable, 121 pin VAG 1598/31 to control module wiring. Do not connect engine control module.
Check between contacts 1 + 48 on test box using auxiliary cables from Auxiliary measuring tool set VAG 1594 A.
Turn on ignition.

EPC warning lamp should illuminate

If the EPC warning lamp does not light:

Turn ignition off.
Remove instrument panel and check bulbs and their voltage supply: Refer to 90 INSTRUMENTS

If no malfunction is found:

Use wiring diagram to check whether there are any electrical broken connections between jack 48 of test box and instrument panel.

If the wiring is OK:

Replace engine control module: Refer to 24 MULTIPORT FUEL INJECTION (MFI)