My 97 STS, just lost turn signals and both heated seats at the same time.
I had the cover off the fuse compartment to clean it and since then I have the problem?
The hazard signals work OK.
I just solved a similar problem on my 96 SLS. My ABS/TC lights would come on, heated seats would fail, turn signals would fail, and the rear console fan would fail. It took me quite some time to figure out that they were all failing at the same time.
Anyway, all of those circuits (on my 96) were powered through a single source. A wire goes from the battery, to a fuse box, through the ignition switch, and out to the individual fuses for those components. After lots of diagnosis, I traced my problem to an intermittent break in the wire between the fuse block and the ignition switch. Running a new wire fixed the problem.
I checked the wiring diagrams on alldata and sure enough, the 97 STS also has a single source of power for the turn signal, console (including heated seat switches and rear fan), and the ELC (electronic leveling control??). Check the Batt3 fuse. If that is not the culprit, then you have a wiring problem or a bad ignition switch.