1996 and later, DOT or EPA require all passenger vehicles sold, for the USA markets must have the OBD (2) connection- access plug be located the Left Front Seat Area.
A 1990 Ford Ranger is OBD I / EEC IV - if that's what you are asking
The 2001 Mitsubishi Montero OBD 2 port is under driver side dash above accelerator
under the drivers side of the dashboard,cant miss it,i think its 12 pin,to the right of the steering column
The 1997 Mitsubishi Diamante OBD 2 port is under driver side dash next to center console
The 1999 Mitsubishi Eclipse OBD 2 port is on lower right edge of dash; next to kick panel
The 2001 Mitsubishi Eclipse OBD 2 port is under driver side dash next to center console
The OBD plug is under the dash on the driver side.
The 1996 Mitsubishi Galant OBD 2 port is on lower edge of drivers dash next to center console
The 2002 Mitsubishi Diamante OBD 2 port is under driver side dash above accelerator pedal
The 1998 Toyota Avalon OBD 2 port is behind fuse cover
OBD II was used in Fords starting in 1996 ( there should be an EEC TEST connection in your engine compartment somewhere near the battery )
Answering "How can you diagnose a 1998 Honda accord without an OBD scanner?"