To check keys in diagnostic mode 1 Press 9 on the one-touch keypad. 2 Press all of the keys on the control panel. 3 Press an extra key. For each key pressed during the test, a "+" character appears on the LCD (initially, five "+" characters appear on the screen to account for the 9 on the one-touch keypad and for four other spaces that have no key correspondence). When all of the keys have been pressed, the display fills with "+" characters. Pressing any other key after the display is full results in the message "OK" on the control panel display also causes both LEDs to toggle on and off. To exit diagnostic mode 1 Press V OLUME , E NTER /M ENU , and 1 on the one-touch keypad simultaneously.
2 Release the keys. EN Service mode functions 177