Furuno - enq sent Garmin See Garmin Y2K . Garmin will issue instructions for older products a few weeks prior to the GPS rollover. Current products are Y2K compatible. Humminbird Humminbird technical support report that the year 2000 rollover will not affect their GPS units. Ashtech See g8 FAQ .
Some products are fully compliant, others require firmware upgrades.
A few products require a reset following week 1023 rollover. See Trimble's Status Table for complete details. Magellan Magellan has a Y2K page in their Product Support area. Motorola Oncore - Motorola Oncore receivers will not need reprogramming or replacement in 1999. This may be fixed by entering a date command when the receiver is not tracking satellites.