[primoV8]

Installing a new battery shouldn't have caused the rear air leveling suspension to lose air. You can always spray a soap+water solution where the air hoses connect to the air compressor and air leveling shocks just to rule out any leaks. If that all check outs, then the compressor and height leveling sensor would be next. If not a dealership, find a reputable shop that utilizes a full range scan tool. It'll be able to read and scan for any DTCs related to the rear air leveling suspension.

 

[primoV8]

Unlike the first gen trucks, your 2017 armada, just like my QX80 doesn't have the relays for the rear air leveling suspension located next to the battery. The fuse and relay for this system are located in the fuse and relay boxes in the engine bay, passenger side.