i have a jeep cherokee & a message comes up service gear box what is this about ?
Gear box needs service. As a 2018 it might be covered by your 36/3600 warranty or your power train warranty. Or it could be a maintenance item that you are required to have done. The service writer at you dealership should be able to assist you.
It means the computer sees something amiss in the gearbox and it needs to be fixed .
… free-of-charge, under the terms of the Powertrain Warranty.