This information is edited from a repost of an acig.org forum post by mrdetonator:
http://www.secretprojects.co.uk/forum/index.php/topic,25.msg59.html#msg59
"ВЫКЛ, 3, 1, 2, 4" Switch
Used to select the IR missile (R-13M, R-3S) carried on the pylon which locked-on the target.
The pilot has to switch the proper position after the "ПР" command is shown on the SEI and pilot hears the beep tone.
LITERA S-23 Switch with positions 1,2,3,4
Located on the right vertical console.
Selects of four radar pulse repetition frequencies. During a formation flight by using radar modes the pilot has to switch one of the LITERA frequencies to prevent mutual radar interferences.
In the MB radar mode the switch is deactivated.
The switch also determines the total number of aircrafts operating in the group with radars activated.
OKHLAZH RLS switch
Activates liquid cooling of the radar during ground tests.
The switch should be OFF in the flight.