Engine Control Module Power Supply Relay
WARNING: This page is about a different car, the 2002 Audi S4. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Voltage is supplied to Engine Control Module (ECM) by ECM power supply relay at ECM harness connector terminal No. 3 (ignition voltage) and No. 62 (battery voltage). Ground is supplied to ECM at ECM harness connector terminals No. 1 and 2. ECM voltage supply relay is located in left rear corner of engine compartment, in electronics box.
To test ECM power supply relay, see ECM power supply relay related DTC(s) under DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS article.