T60 Type 1951. Die-hard CMOS Battey Checksum problem

[semenzara]

Hi folks,

Thank you for this wonderful forum. This is my first message here but I hope to be more active and helpful in the future.

I am encountering a problem with my T60 Type 1951 (year 2007). It's the frequent

0251: System CMOS Checksum bad - Default configuration used.
Real Time clock Error - Check Date and Time settings

Obviously, I thought of a CMOS battery problem and changed it: no solution.
I ordered and tested two more CMOS batteries: no solution.
Then, I tested all my batteries with a multimeter and all of them were good, including the one formerly in the PC.
I also tried to update the BIOS to the last version: no solution.

This problem is quite annoying because, since the main battery is dead, I have to reset date/time every time I unplug the Thinkpad from AC power.

Another thing I noticed is that, every time I change a BIOS option (e.g. the boot order) it is correctly updated. If I unplug the AC adapter, I lose only the date/time setting.

I checked for some solutions online and in most cases the problem disappeared when changing the CMOS battery.
Another cause can be the BIOS password? Nope, my BIOS is unlocked.
I tried the hard reset (CMOS reset) as suggested in the Lenovo forums (unplug everything and hold the power button for 30 seconds), but it did not solve the problem.

[RealBlackStuff]

Go into BIOS, press F9 to load defaults, then press F10 to save the changes, then press the Power button to switch off.
Switch on again, any better?

As a last resort, hunt for the HMD (Hardware Maintenance Diskette) program.
This program can also make a bootable USB-stick (see README.TXT).
Run it and select to set the UUID, after which it will automatically reset the CMOS checksum.

If that still does not help, you may need a new motherboard, OR check that the CMOS post is properly connected to the motherboard.

[semenzara]

Go into BIOS, press F9 to load defaults, then press F10 to save the changes, then press the Power button to switch off.
Switch on again, any better?

As a last resort, hunt for the HMD (Hardware Maintenance Diskette) program.
This program can also make a bootable USB-stick (see README.TXT).
Run it and select to set the UUID, after which it will automatically reset the CMOS checksum.

If that still does not help, you may need a new motherboard, OR check that the CMOS post is properly connected to the motherboard.

Thank you very much for your help. Sadly, none of these solutions worked.

Regarding the solution you mentioned, in the former case I think I won't bother searching for a new MB for a relatively small problem like this. Since the TP loses the date/time when it is completely disconnected from a power source, I think that buying a new main battery can fix the issue. Do you agree?
The latter case you mentioned looks interesting... maybe the problem can be in the connector between the CMOS battery and the MB. How can I identify if this is the cause?

The HMD looks like a very useful tool! Thank you very much for spotting it.

[RealBlackStuff]

The CMOS battery plugs in a small white socket on the mobo.
You should see two small pins in that socket, standing up straight.
If there is only 1 pin, that's your problem.
Or if both pins are not straight, then bend them straight.

CMOS batteries are not rechargeable, so buying a working main battery will not help.
Did you use the HMD program and reset the UUID?
If that did not work, then I think you'll need a new motherboard.