Lenovo T420i manual Indicator Meaning

Table 7.	Status indicators
Indicator		Meaning
1	Speaker mute	Orange:
		The speaker is on mute. To set the speakers on mute or unmute,
		press the speaker mute button.
2	Microphone mute	Orange:
		The microphone is on mute. None of the recording devices is
		available while the microphone mute is on by default.
3	Wireless LAN, Wireless WAN,	Green:
	or WiMAX status
		The wireless LAN feature (the IEEE 802.11 b/g standard, 802.11
		a/b/g, or 802.11n), wireless WAN feature, or WiMax feature is
		on, and the radio link is ready for use.
		Data is being transmitted.
4	Bluetooth wireless or Wireless	Green:
	USB status
		The Bluetooth wireless feature is on, and the radio link is ready
	R
		for use.
		Data is being transmitted.
5	Device access	Green:
		Data is being read from or written to the hard disk drive, the
		diskette drive, or the drive in the Serial Ultrabay Enhanced
		device. When this indicator is on, do not put the computer into
		sleep (standby) mode or turn off the computer.
		Note: Do not move the system while the green device access light is on.
		Sudden physical shock could cause drive errors.

50ThinkPad T420 and T420i Hardware Maintenance Manual