Teledyne GC-Pro/TCD - Gas Chromatograph - Manual (Page 101)

GC-Pro TCD Operation
Teledyne Analytical Instruments 87
The validation LED should glow green which means the password
has been entered correctly otherwise, the password is incorrect and you
will be required to enter it again.
Since this function may drastically alter the settings on the analyzer,
once the password has been re-entered correctly and “OK” is pressed, a
final Warning screen will appear.
Pressing “OK” will then reset the analyzer to the default
configuration with the parameters set as described in Appendix C.