How do I disconnect my immobiliser in my 1991 troopcarrier?

The immobiliser is next to the steering column. It is as small device that needs to be inserted to match up 3 pins. It is most likely an early type and unfortunately I don't now the make or model.
The troopy won't show glow plug lights or filter lights. When I disconnect the wire to the coil and "jump" a wire from the battery it will kick over but not start.