WARNING: This page is about a different car, the 2003 Subaru Impreza. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Key Interlock Does Not Lock Or Release Wiring Diagram
Courtesy of SUBARU OF AMERICA, INC.
Fig 2: Key Interlock Does Not Lock Or Release Trouble Shooting Chart (1 Of 3)
Courtesy of SUBARU OF AMERICA, INC.
Fig 3: Key Interlock Does Not Lock Or Release Trouble Shooting Chart (1 Of 3)
Courtesy of SUBARU OF AMERICA, INC.
Fig 4: Key Interlock Does Not Lock Or Release Trouble Shooting Chart (1 Of 3)