A. If you have not successfully used your unit for several months, the Almanac Data for the Satellites may have become invalid. The unit is capable of recollecting this information on its own, but it is a lengthy process. You can help speed this process by performing the following function:

With Power off, perform the following sequence of keystrokes for the unit you have.

GPS II/II+/III/IIIPilot/12/12XL/38/40/45/48/89/90/120/120XL/126/128/130/135/175/180/185/195/230/235
Press and hold the PAGE key down and power the unit up, then release the PAGE key.

GPS 50/55/65/75/85/95/95XL
Press and hold the "0" (zero) key down and power the unit up, then release the "0" key.

GPSMAP 210/215/220/225
Press and hold the MARK key down and power the unit up, then release the MARK key.

After performing these key sequences you will need to take your unit outside where it has a clear view of the sky with no obstructions and allow it between 15 to 30 minutes to download and update its Almanac Data from the Satellites.