What sort of OBD1 protocol is my 1992 jdm toyota celica GTR. it has a 17pin diognostics plug under the bonnet?

[Sam]

I have scantool elm327 it has usb to 16pin obd plug/cable, i also have the converter cable for toyotas old 17pin diognostic plug to16pin obd so i can hook it up to the car with the elm 327 interface but it cant read my cars 1992 ecu as the protacol it used is to old. Does anybody know what sort of obd1 interface/protacol is used to connect a jdm 1992 toyota celica to a pc serial/usb port for reading live engine data temps revs pressures etc. Hope somone can help. thanks sam