If you are talking about stuff like service search or spectrum sweeper, then you're going to actually need to go in and program a new object for what you're interested. Basically make a
NEW -> SRCH -> LMIT/SRVC/SWPR and then refer below. Otherwise, I am not aware of any preset frequencies in PSR-310.
For an existing object, you should select the object and
EDIT ->
CURR. Use the down arrow until you get to
LED Mode and select if you want it to
Flash or be
Solid. After that, you need to select
LED Color and choose
1-7,
0 is off. Be sure to
Save it and that should be it. Repeat as desired.
If that does not work, check if
Alert Mode in
GLOB is set to
Both or
Light. If it is not set to either, it will not work.
If someone hasn't already provided the
Easier to Read manual for the PSR-310, the link is below and is certainly a good read to learn about the scanner:
Easier to Read PSR310/410 Scanner Manual