Lenovo ThinkCentre M55, Hardware Maintenance Manual

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3. There are three LEDs to help you determine if the power supply and system board are working correctly.
The power button LED is located on the front of the computer and the two diagnostic LEDs are located
on the power supply at the rear of the computer. After pressing the power button, observe the LEDs and
refer to the following table:
Power LED
Green
diagnostic
LED Yellow
diagnostic
LED
Action
ON ON OFF This is the normal condition of the LEDs when the power is OK.
OFF OFF OFF • Make sure the power cord is attached to a working electrical
outlet.
• Check the power cord for continuity.
• If the problem persists, replace the power supply.
OFF (after the
power button
has been
pressed) ON OFF
Replace the system board
ON ON ON
Replace the power supply
If the Diagnostic LEDs are in the normal condition and the problem persists, replace the system board
and the microprocessor, one at a time, until the computer works correctly.
Diagnostic error codes
Refer to the following diagnostic error codes when using the diagnostic tests. See “Running tests” on page
43 for the specific type for information about the Diagnostic programs.
In the following index, X can represent any number.
Diagnostic Error Code FRU/Action
000-000-XXX BIOS Test Passed No action
000-002-XXX BIOS Timeout 1. Flash the system. See “Flash update procedures”
on page 375
2. System board
000-024-XXX BIOS Addressing test failure 1. Flash the system. See “Flash update procedures”
on page 375
2. System board
000-025-XXX BIOS Checksum Value error 1. Flash the system. See “Flash update procedures”
on page 375
2. Boot block
3. System board
000-026-XXX FLASH data error 1. Flash the system. See “Flash update procedures”
on page 375
2. Boot block
3. System board
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Hardware Maintenance Manual