Read part 43, Appendix A, (c) 31 and 32, excerpted below. The appendix defines what preventative maintenance is in terms of work performed. Any work on your aircraft included in the list is defined as preventative maintenance:
Appendix A to Part 43 - Major Alterations, Major Repairs, and Preventive Maintenance
...
(c)
Preventive maintenance. Preventive maintenance is limited to the following work, provided it does not involve complex assembly operations:
...
(31) Removing and replacing self-contained, front instrument panel-mounted navigation and communication devices that employ tray-mounted connectors that connect the unit when the unit is installed into the instrument panel, (excluding automatic flight control systems, transponders, and microwave frequency distance measuring equipment (DME)). The approved unit must be designed to be readily and repeatedly removed and replaced, and pertinent instructions must be provided. Prior to the unit's intended use, and operational check must be performed in accordance with the applicable sections of
part 91 of this chapter.
(32)
Updating self-contained, front instrument panel-mounted Air Traffic Control (ATC) navigational software data bases (excluding those of automatic flight control systems, transponders, and microwave frequency distance measuring equipment (DME)) provided no disassembly of the unit is required and pertinent instructions are provided. Prior to the unit's intended use, an operational check must be performed in accordance with applicable sections of
part 91 of this chapter.