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If the MTM and Product ID numbers differ from each other on the rear label, use what is shown for the
Product ID eld. See the following example:
MTM on the rear label:
TTTT-CTO S/N SSSSSSS
Product ID on the rear label:
TTTT-MMM (Use this number when setting Serial Number.)
In the example, the Serial Number to be input is “1STTTTMMMSSSSSSS”.
Retaining the UUID
The Universally Unique Identier (UUID) is a 128-bit number uniquely assigned to your computer at
production and stored in the EEPROM of your system board.
The algorithm that generates the number is designed to provide unique IDs until the year A.D. 3400. No two
computers in the world have the same number.
When you replace the system board, follow the following steps to create new UUID for the system board if
the system board does not have a UUID:
1. Install the latest version of LENOVO ThinkPad Hardware Maintenance Diskette or Maintenance Key,
and then restart the computer.
2. From the main menu, select 4. Assign UUID. A new UUID is created and written. If a valid UUID already
exists, it is not overwritten.
Reading or writing the ECA information
Information on Engineering Change Announcements (ECA) are stored in the EEPROM of the system board.
The electronic storage of this information simplies the procedure to check if the ECA has been previously
applied to a machine. The machine does not need to be disassembled to check for the ECA application.
To check what ECAs have been previously applied to the machine, use the ECA Information Read/Write
function on the LENOVO ThinkPad Hardware Maintenance Diskette or Maintenance Key.
1. Insert the latest version of LENOVO ThinkPad Hardware Maintenance Diskette or Maintenance Key,
and then restart the computer.
2. From the main menu, select 6. Set ECA Information.
3. To read the ECA information, select 2. Read ECA/rework number from EEPROM and follow the
instructions on the screen; To read box build date, select 5. Read box build date from EEPROM, and
follow the instructions on the screen.
After an ECA has been applied to the machine, the EEPROM must be updated to reect the ECA's
application. Use the latest version of LENOVO ThinkPad Hardware Maintenance Diskette or Maintenance
Key to update the EEPROM.
Note: Only the ECA number is stored in the EEPROM. The machine type of the ECA is assumed to be the
same as the machine type of the machine that had the ECA applied to it.
1. Insert the latest version of LENOVO ThinkPad Hardware Maintenance Diskette or Maintenance Key,
and then restart the computer.
2. From the main menu, select 6. Set ECA Information.
3. To write the ECA information, select 1. Write ECA/rework number from EEPROM, and follow the
instruction; To write box build date, select 4. Write box build date from EEPROM, and follow the
instruction on the screen.
Chapter 9. FRU replacement notices 65