Installing an external alarm to my marine chartplotter/sounder

Alarm relays are always required when using a horn and/or a lamp that draws amperage values of greater than 100mA.  While it is possible to perform a temporary test of the horn/lamp without the use of a relay, please do not attempt if you are not completely aware of the amperage values of the installed equipment.  Failure to follow this guideline can lead to permanent damage to the connecting chartplotter, as they are not equipped to handle amperage values above 100 mA.  If damage should occur, Garmin will require the device to be sent in for an out of warranty repair.

To connect the alarm for testing purposes:

·        Connect the Alarm VDC+ wire to the Positive (+) Power

·        Connect the Alarm VDC- wire to the Garmin Alarm Wire

When the Garmin activates an alarm state, the alarm wire will create a low voltage (ground) signal that will complete the circuit, causing the alarm to activate. When you're satisfied with the results, please be sure to remove this connection.

If a relay needs to be purchased, they can commonly be found at local electronics or auto parts stores.   Relays can also be purchased online using the search terms “100mA relay 12Vdc” on any common search engine (Google, Bing, etc.).