Lenovo ThinkPad T470 20HD, Hardware Maintenance Manual, Page: 45 / 116

• The system is powered off.
Note: If the computer enters the hibernation mode while it is docked to the docking station or the port
replicator, do not undock it before resuming normal operation. If you do undock it and then try to resume
normal operation, you will get an error message, and you will have to restart the system.
If you have defined one of the following actions as the event that causes the system to go into hibernation
mode, perform that action.
• Closing the lid.
• Pressing the power button.
Also, the computer goes into hibernation mode automatically after a period of inactivity specified in power
plan settings.
When the power is turned on, the computer returns from hibernation mode and resumes operation. The
hibernation file in the boot record on the hard disk drive or solid-state drive is read, and system status is
restored from the hard disk drive or solid-state drive.
Symptom-to-FRU index
This section contains following information:
• “Numeric error codes” on page 40
• “Error messages” on page 41
• “Beep errors” on page 41
• “No-beep symptoms” on page 43
• “LCD-related symptoms” on page 43
• “Intermittent problems” on page 44
• “Undetermined problems” on page 44
The symptom-to-FRU index in this section lists symptoms and errors and their possible causes. The most
likely cause is listed first, in boldface type.
Note: Do the FRU replacement or other actions in the sequence shown in the column headed “FRU or
action, in sequence.” If replacing a FRU does not solve the problem, put the original part back in the
computer. Do not replace a nondefective FRU.
This index can also help you determine, during regular servicing, what FRUs are likely to need to be replaced
next.
A numeric error is displayed for each error detected in POST or system operation. In the displays, n can be
any number.
If no numeric code is displayed, check the narrative descriptions of symptoms. If the symptom is not
described there, go to “Intermittent problems” on page 44.
Note: For a device not supported by diagnostic codes in the ThinkPad notebook computers, see the manual
for that device.
Chapter 4
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Related service information
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