Select your product to confirm this information applies to you
Backlight Not Illuminating When Powering on Garmin Mode Outdoor Handheld
Most handheld Garmin devices have the ability to adjust the level of the back light setting or intensity. However when the device is powered off and then powered on again the backlight is set to the off position again.
One of the reasons for this setting is to conserve battery power if the device is powered up in a daylight situation. The original backlight setting is saved however and can be brought back up by simply pressing and releasing the Power button one time. This will bring the backlight up to the original preset level again. Another tap on the Power button will increase the level further.
Once the desired backlight level is set for example to a brightness level of 80% it should remain at that preset level until it is changed again.