from cummins diesel forum,
http://www.cumminsforum. com/forum/2013-general-discussion/1077802-hacking-uconnect-8-4a-8-4an.html
If you press and hold both the temperature-up (red arrow) and temperature-down (blue arrow) buttons at the same time, for 5 or so seconds, you are presented with the "Engineering Menu"
Another trick is to hold the up, down, and front defrost buttons simultaneously for about 5 seconds and then you are presented with the "Dealer Mode" menu:
Another trick is to hold down the up, down, and Browse/Enter buttons simultaneously for about 5 seconds. That puts you into touchscreen calibration mode, where you just follow the on screen instructions:
(
for those with tailgate camera )
The last trick I know about so far is to hold down the up, down, and rear defrost buttons simultaneously for about 5 seconds. That will write a screenshot (1.2MB .bmp file) to the flash drive in the console USB slot... which is how I got all the pictures for this post! It will literally capture whatever is on your screen, including the backup camera image and radio info:
One thing to remember before you insert your flash drive to capture screens: don't use one that still has the "swdl.iso" file on it from your last upgrade!
The most annoying thing I noticed during all this: the screenshot files have the precisely correct time and date (in GMT) on them... despite the fact that this radio can't keep time worth a darn and randomly loses a couple of minutes every day or two. So the radio is getting the correct time and updating itself, but they still use some broken algorithm to run the displayed clock.
Duncan