Panasonic KX-T336 System Reference Manual page 498

7) After the diagnosis of the CRT display ends, the following
display appears and waits for command entry.
DIG> C9T
- CRTTsst
start
--- Compete
I
Note :
Pressing the F8 key or CRTL + C key during the diagnosis stops
the diagnosis and displays "Abort."
. Displayed Message
Displayed Message
Meaning
H-K-X+ Error: Illegal main command
There is an error in the main command.
+-+ Error: illegal sub command
There is an error in the sub command.
c
13-D-4