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Hey, my name is Dusty and I'm one of the auto experts with RepairPal's Car Genius team here to help! What a headache those communication faults can be sometimes. As for the erratic shifting, and the gear selection not showing, they're most like related to the communication issue at hand. There's a barrage of things that can cause communication issues, from something as simple as low supply voltage due to a failing alternator. To a more complicated network issue, broken wire, or possibly even corrupt data being transmitted from one module to the rest of the network. I'd recommend having a competent professional take a look at it, this is one of those things that some folks could easily make a mountain out of a molehill. They'll have the skills, knowledge, tools, and access to the data to pinpoint and remedy the issue. If you have any other questions or would like to help with finding a RepairPal Certified shop in your area, give us a call! 877-913-1554