Honda FOURTRAX 2018 Owner's Manual page 180

Brakes
Brake Light Switch Adjustment
Refer to Safety Precautions on page 103.
Rear Brake Only:
Check the operation of the rear brake light switch (1) at the right
side behind the engine from time to time. Adjustment is done by
turning the adjusting nut (2). Turn the nut in direction (A) if the
switch operates too late and in direction (B) if the switch operates
too soon.
RIGHT REAR
(A)
(2)
(1)
(B)
(1) rear brake light switch (2) adjusting nut
170 Servicing Your Honda