Quite a while ago now, someone sent me their corrupt 2014 firmware which was non-Nav, I looked again today, there are appear to be no differences in the apps, bar the bootloader, kernel, missing navi and missing "FpvLe" directory with the images needed for the Fpv Gauges (/packages/factory/hmi/root_dir/usr/hmi/HighSeries/FpvLe). You would have to copy the FpvLe directory over (it's about 1MB - so should fit with what little space is left on those units - they are on github in the 2014 Navi archive).
You can possibly enable these gauges ONLY IF you are running the 2014 software (I've done it, but only on the Navi unit) with a script to run ***some*** of these commands (pick the 2 you want) in QNX:
#turn on FPV button (off=0 or on=1)
send2 -w /hmi/dp/1/1907 0
send2 -w /hmi/dp/1/1907 1
#switch manual (volts=0) or automatic (temperature=1)
send2 -w /hmi/dp/1/1908 0
send2 -w /hmi/dp/1/1908 1
To automate this when the unit boots, I created a shell file (unix line endings! not ms-dos, called say "gauges.sh") in the directory "/packages/system/trailer" with the chosen 2 lines.
Note: Only the voltage gauge works, but it could be a fun thing to do anyway. This can be done (copy guages.sh to the right place) with the recore program I posted earlier (WHICH YOU MUST NOT USE!).
Thanks to the anonymous PM guy who I did this for, who then blocked private messages before I could send these details. Have a nice day
(You should be able to remove the file easily too, the same way, if it doesn't work out.)