Panasonic KX-T336 System Reference Manual page 1456

(2) External clock down
Error Code
Possible cause of
the malfunction
Countermeasures
Note
0301
1) TSW card connection error
2) TSW card clock link failure (External)
"TSW external clock down "has occurred, and the T-1 or E-1 master card
does not synchronize with the clock time sent from the Central office.
After confirming the TSW card
connection, press the RESET
button
Is the trouble registered in the Error
Log ?
Yes
Does system work with external
clock mode ?
Replace the T-1 or E-1 card.
Replace the TSW card.
Another T-1 or E-1 card with next priority will work as a master card, if more
than two T-1 or E-1 cards were registered to the system by CLP command
(Refer to Section 64.03) beforehand. Otherwise, the system will synchronize
with the system internal clock.
14-E-6-1
(70695)
No
No
NG
End
Yes
OK