T420s - Fingerprint reader suddenly disappeared

[kozukumi]

I just got a T420s and the fingerprint reader was working fine. Swipe and it powered on the computer and logged into Windows (7 and then 8.1 after a clean install) and then for some unknown reason it has just vanished. Even when I go to the BIOS and select to reset fingerprint data it says no reader is detected.

What makes things even stranger is that if I remove the battery and mains for a minute then connect them again the green led on the fpr comes on so it is connected and I have even managed to turn the machine on a couple of times with a swipe but then the green led goes off and again it is not detected.

I have taken the palmrest apart and reseated the connector but nothing. I noticed it shares the same connector as the trackpad which is working fine so I really am at a loss. It is just so inconsistent.

Sometimes the green led lights up and stays lit until I swipe then boom its gone. Sometimes it lights up for a few seconds then turns off and doesn't work at all.

Has anyone else had this problem? Is it hardware failure/fault? A BIOS bug? I can't recall making any changes before these problems started form I did install Windows 8.1 the day before so lots of driver installs, etc. Like I said though it was working fine.

Any help would be greatly appreciated. Thanks!

[kozukumi]

Ok so a small update -

I can now consistently turn the machine off, the green light on the fpr comes on and I can swipe to turn the machine on. Interestingly it is recognising my fingerprint because it will only turn on with a registered fingerprint so not only is the fpr actually working but it still has my fingerprint data stored!

However as soon as the machine powers on (either from swipe or power button) the green light goes off and the fpr is no longer detected. I go to the BIOS and the say message comes up when I try to reset the fpr data that there is no fpr connected.

This is driving me crazy as the fpr obviously works but as soon as the machine powers on it vanishes. Ugh.

[Dekks]

Does the green light reappear if the machine goes into sleep?

[kozukumi]

Does the green light reappear if the machine goes into sleep?

Just tested and yes it does. Swiping it also resumes from sleep.

This is one of the weirdest problems I have ever had with hardware. It just makes no sense. It works when the machine is off but not when the machine is on?!

[Dekks]

Swipe in then after 5 min log user off then does green light come back.

[kozukumi]

No signing out does nothing. It is only if the machine enters a full power off state or sleep state.

I had a look in device manager (with disconnected devices also visible) but Windows has no record of a biometric device ever being in the system so something has to be happening for it to totally disappear that even the BIOS can't see it in that second or two right after power returns.

[Dekks]

Its a usb device, whats the BIOS powersaving settings for USB.

[kozukumi]

Its a usb device, whats the BIOS powersaving settings for USB.

I can't see anything related to power saving for USB in the BIOS.

The only USB related settings are for the powered USB which are all enabled but I have tried flipping them and it makes no difference.

[kozukumi]

I have taken a few pictures of the BIOS settings screens here http://imgur.com/a/oVfQF

and a short video of the fpr working when powered off but then not being detected in Windows at http://1drv.ms/1KrvaJA

Let me know what I should try changing.

Note that I have tried every combination on the Fingerprint BIOS screen for predesktop authentication, etc.

[Dekks]

OK what Thinkpad software for the FPR have you installed?

[kozukumi]

6.0.0.8102 64-bit from the link below

http://support.lenovo.com/gb/en/product ... s/DS036923

[Dekks]

If device manager isn't seeing it and its properly connected that leads to its defective and needs a new palmrest. You could try running a linux live cd and running lsusb to see if the linux sees the fpr.

[kozukumi]

Booted from a few different Linux live USBs but none of them see the fpr