1994 Subaru Loyale test connectors

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Your On Board Diagnostics (OBD one) for this vehicle can be a variety of plug configurations, and their location may be under the hood or under the dash. Each manufacturer was doing their own thing until 1996 when OBDII (OBD two) became the universal standard. On my 1989 Ford Tempo, I remember putting jumper wire between two terminals of the plug under the hood, then counting the number of blinks of the check engine light. If you find the diagnostic plug, it will be a "disconnected" plug with a dust cover. Some shops may have a diagnostic tool to "read" your pre-1996 Subaru for a fee. Or go online for the diagnostic procedure. It can't be very complicated.