My furnace says that my pressure switch is open with inducer on. When I unplug one of the wire to the pressure switch and turn the furnace back on nothing happen. The light still flashes. When I unplug one of the wires to the relays the inducer start but the furnace still want fire. Help please!

You might briefly,and for a very brief few minutes jumper the two wires together ,this will by-pass the pressure switch long enough to determine if the pressure switch is bad,, take jumper off asap as it's a very important safety device that shoud be replaced before using the furnace

Remove the rubber tube going to the pressure switch from the furnace collector box. With it attached to the pressure switch blow and suck very lightly on the tube you should hear the switch click when you do this. Some switches are stubborn and stick a few times when you first start to use your heat.