where are the fuses located in a 1998 Volvo S90

Have you checked under your hood or on the side of your dash

Check the signal bulbs on the left side. Remove the bulb that is lighted and replace. My S90 was doing the same thing, but only when I turn on my lights. I removed the left rear signal bulb and replaced it. It works fine now.

usually a blow light bulb. check to see which one is not coming on. and replace. if its not that, it might be your flasher.

it have 3 fuse boxes. next to the battery, next the air filter and brake master cylinder area and an other one inside the cab, you will see it when the driver door is open, is on the left side next to the a/c vent.

I have a crazy issue with my Volvo. My switches on my steering wheel are not working. My signals make a sound but does not light up on my dashboard and it does not flash outside. Also, I can not adjust the volume of my radio from the steering wheel.