Subaru Impreza 2003 Service Manual page 1779

DIAGNOSTIC PROCEDURE WITHOUT DIAGNOSTIC TROUBLE CODE (DTC)
AUTOMATIC TRANSMISSION (DIAGNOSTICS)
F: CHECK INHIBITOR SWITCH
DIAGNOSIS:
The input signal circuit of inhibitor switch is open or shorted.
TROUBLE SYMPTOM:
• Shift characteristics are erroneous.
• Engine brake is not effected when selector lever is in "3" range.
• Engine brake is not effected when selector lever is in "2" range.
• Engine brake is not effected when selector lever is in "1" range.
4AT-109