Adjusting The Backlight - Garmin GPSMAP 420 Owner's Manual

Getting Started
Minimum Safe depth—select the minimum safe depth for your
boat. Refer to your boat specifications for more information.
Shallow water alarm—only available if you are receiving NMEA
yes or No.
sonar depth data. Select
Minimum Overhead Clearance—select the minimum overhead
clearance for your boat. Refer to your boat specifications for more
information.
aiS alarm Range—select the distance in which an alarm will
sound if an AIS vessel nears your boat
aiS alarm Time To—select the time within which an alarm will
sound if an AIS vessel is on track to intersect the Safe Zone around
your boat (page 43).
If a water speed wheel is detected, a message will ask if you want to
calibrate it now. Select yes or No.

Adjusting the Backlight

1. Press and release the Power
2. Select Backlight.
4
(page 43).
key.
To allow the unit to automatically adjust the backlight based on
ambient light, select auto backlight
available only on the GPSMAP 525, 526, 555, and 556).
To switch between Day and Night mode:
1. Press and release the Power
2. Select Color Mode.
3. Press left or right on the Rocker to switch between modes.
(automatic backlight is
key.
GPSMAP 400/500 Series Owner's Manual