"System Missing" or Blank Screen on a GMI 20 or GHC 20

Reinstalling software may resolve the issue with the message "System Missing" on a GMI 20 or a GHC 20 (connected to a GHP 20 or GHP Reactor Reactor autopilot system). An NMEA 2000 compatible Garmin chartplotter or NMEA 2000 Network Updater and a software update card are required. The software update can be acquired from the Marine Device Software Updates page as a free download or purchased on a preloaded card.

If a Garmin marine chartplotter is not connected, set up an NMEA 2000 network with just the GHC 20 or GMI 20 and the NMEA 2000 updater. The NMEA 2000 network should consist of three t-connectors and two terminators. One of the t-connectors will have the NMEA 2000 yellow power cable, another to the NMEA 2000 updater, and the last connector to the drop cable for the GHC or GMI device. In the case that there are multiple GHC 20 or GMI 20s all showing the same message, update each device separately. For more information on setting up an NMEA 2000 network, see NMEA 2000 Technical Reference Guide. 

Begin by powering on the NMEA 2000 network created for this purpose, which turns on the GHC or GMI. Turn off the GHC or GMI and follow the instructions below. 

GMI 20

1. Insert the software SD card into the NMEA 2000 updater with the device fully powered off.* Press and hold the Back button. Continue to hold the back button, then press and release the Power button, but continue to hold the back button. *If using a Garmin marine chartplotter, insert the software update card into the chartplotter and select Update Software

2. When "Loader Ready" appears above the logo, release the Back button

3. The message above the Garmin logo changes to "Software Loading" and the light on the card reader should be flashing orange

GHC 20

1. Insert the software SD card into the NMEA 2000 updater with the device fully powered off.* On the GHC, press and hold the Standby button. Keep holding press and release the Power button, and continue to hold the Standby button.  *if using a Garmin marine chartplotter, insert the software update card into the chartplotter and select Update Software

• • When the Garmin logo displays, release the Standby button. The message above the Garmin logo will alternate between "Loader Ready" and "Software Loading," and the light on the card reader should be flashing orange. The GHC 20 might initially show "Software Missing" but should change to "Loader Ready" after a few moments. If it remains on "Software Missing," power off the GHC 20, remove the card from the reader, wait 60 seconds then begin the process again

The light on the card reader blinks green, and the device has rebooted, indicating completion of the forced reinstall of the software. If the GHC or GMI 20 still shows "System Missing" after performing the update, it will need to be sent in for repair.