I have an android so cannot add to the app you are speaking of. However with regards to apps for the truck I can recommend Torque when used in addition with the blue tooth OBD-II adapter. its great for monitoring the ECU and tracking things form yoru iphone or android phone. I imagine mudchet could even use it on your ipad since you have it docked in the truck. You can check and clear engine codes as well. Pretty good tool to have when you want to know things on the fly. Now if you don't have a smartphone or prefer not to use apps in the field, there is a field engine check you can do anywhere. I don't know the full details of the code and if anyone knows of a thread about it, please pass along. But when I was at ecxc this past summer, a buddy of mine broke the ABS cable. This sent an error to the computer that prevented the truck from engaging in 4x4. Although it still worked, the broken ABS cable was programmed in the computer to not engage the 4x4. So this guy comes over and does a combination code sequence in the truck and all kinds of things starting happening. What i remember is turn key to "ON" position, depress door adjar button 10 times, one of the smaller gauges starts going haywire, wipers go 4 times low then 4 times high, then he turns the 4x4 to LO then back to HIGH....
Thats about all I could remember since the only manual codes I knew were rather or not to turn the horn on with the remote. Now unfortunately it did not work with my friends truck. But it worked someone else's that day and I was told this operation was a way to clear codes or reset the computer when not convenient to get to a nissan dealership. If anyone is interested in smartphone gadgets, look up the Torque on youtube. If anyone knows more about this field check method, please pass the details.