Electric blankets come with a control cord that powers the blanket when it is plugged in. Before washing your electric blanket, unplug the cord and remove it from the blanket. You should never wash an electric blanket with the control cord still attached to it.
Check if any of the heating elements within the blanket have torn through the blanket, as this can be dangerous. Also, shake out the blanket to remove any loose debris that might have gathered on the blanket during use.
If your electric blanket is an older model and does not have a detachable control cord, do not wash it in a washing machine. Carefully hand wash this blanket without submerging the control cord.