A flashing arrow pointing up on the instrument panel on my 850t5 what does this mean?

If the transmission is not in a lower gear than "drive" when the arrow flashes, or your transmission is not set for "winter driving mode", you could be experiencing a PNP switch going bad. The PNP is a switch that sits on top of the transmission near the shift linkage. It's a pain to to istall and costs about $120 most places.