You’ll also want to detach the metal ground strap located in the center of the terminal block, where the neutral/ground wire was connected. This metal strap has been used to ground the dryer by connecting the neutral wire to the body of the dryer. A separate ground wire—the fourth wire, is replacing it. You should be able to simply remove this metal strap.
The new cord has a green ground wire; two hot wires, which are black and red; and a white neutral wire. Attach the neutral to the middle connector and the two hot wires to either end of the terminal.
In order to safely ground the machine the green ground wire must be securely connected to the dryer frame. There may be a screw on the frame where you can attach the ground but most likely you’ll have to drill a hole into the frame and attach the wire using a sheet metal screw and washer.
To make sure the ground wire is properly installed you can check it using a multimeter set to test resistance (X1). Touch one end of the multimeter to the metal body of the dryer and the other to the ground prong of the plug. The meter should show very low resistance, in the tens of ohms or less. Very high or infinite resistance indicates a poor or incomplete connection of the ground wire. If it doesn’t yield a low resistance measurement, double check to make sure you’ve made a good connection between the dryer frame and the ground wire.
Once you have verified the ground wire is properly connected to the appliance and power cord, replace the metal access plate carefully; the new ground wire will protrude from the side of the plate as it is attached to the outside of the dryer frame. The plate should fit snugly without cutting into the new ground wire.