Sounds like you need a new flasher.
Typically, it is a light bulb. Turn that indicator on and check to see if either the front or back light is not working. Some newer cars have turn lights on the front side as well. Compare to the working side to find all the lights that are used. Good luck
Blown bulb.
You need a new turn signal flasher. They are about $10. Yours is located in the front seating area on the driver side under the dash behind the instrument panel, mounted on the passenger side of steering column.
The power steering reservoir is located low behind the right side of the motor very close to the fire wall on 1998 Buick Lesabre.
10w30 says it right on the oil cap.
Refer to dash removal of a '94 Lesabre. The only difference is you have to remove a the glove box and the vent to the right on a '93.
ensure all bulbs on bumpers are good
If you mean it stays on and does not blink then check the other turn signal bulbs on the right side front/back. If it blinks but does not turn off when you make a turn then the problem is in the steering column canceler.
There is a bulb holder below the headlight bulb holder on the right side.It is inside a hole big enough to get your hand in but it is in tight quarters. This holder I believe turns to the right. I used a flashlight to see where it was.
right next to the oil pan, below car
94 buick lesabre was right at the change over( obd1 to obd2) some have an obd2 connection with an obd1 computer. this can only be read by buick garages. go to auto zone or checker auto and they can tell you.
I believe on that model you can access the signals by lifting up the trunk carpet and then unscrewing the plastic wing nuts. The light assembly can then be removed for easy access to the bulbs.