Checking the fuses is most definitely a good place to start. If cleaning the power seat switches does not correct the headrests then you will have to go a bit deeper. The headrests are driven by a gear assembly inside the seatback and they do fail as they get older. If you do a search you should be able to find info on replacing the gear assembly. Does the ambient temperature gauge show a reading or is the screen blacked out? The display is a common failure point and can be replaced relatively easily by removing the instrument cluster where it is screwed on. A working display can often be found for $30-$50 online or at your local salvage yard.

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1989 300CE