To enable diagnostic mode on an Geko, Hold OK when powering the unit on. You'll get a screen with a lot of information (http://home.wish.net/~marx/etrexd.jpg)

Displays


BRAVO Ver 6            -Operating system version
Software ver. 2.09 -Software version
10:41:09 pm -The time (f course)
temp 27'c -Internal temp
bat 2.94v -Battery voltage
ext--------------v -External voltage(from outside source)????
freq 16368323 -The frequency it's tuned to?????
Drft-------------- -Frequency drift???????
Rdrj-------------- -Rejected? Rejected what?
Sgnl 1671 -Signal strength? It keeps changing.
SNR 0 -Signal to Noise Ratio? It sometimes changes.
BRV pass -Something that was checked passed, but what?
RAM pass -Random Access Memory check passes?
ROM pass -Read Only Memory check passed?
^ 70 () -70 what? has test buttons on both sides.
^ () -More button test icons.
() 994BC6DC - ??????????

Thanks to Dolph Hebb for this.