Subaru Legacy 2003 Service Manual page 448

ENGINE MALFUNCTION INDICATOR LAMP (MI)
4) When ignition switch is turned to ON (engine off)
or to "START" with the test mode connector con-
nected, the MI blinks at a cycle of 3 Hz.
ON
MIL
OFF
Ignition
switch
ON
1 sec.
EN-00198
EN(H4SO)-51
ENGINE (DIAGNOSTICS)