This How-to guide explains the steps needed to replace the turn signal switch on a 1990 Reatta.
These steps should be similar to 1991 and earlier models, although earlier models didn't have an air bag in the steering wheel.
Click the link below to view the How-to guide.
1990 Reatta Turn Signal Switch Replacement PDF
Thanks to Philbo, member of the Reatta forums, for this information.