There isn't a flasher box. What you want is the flasher which is located near the fuse box, or is clipped on to the underneath edge of the dash near the steering column.
In my 83 cadillac sedan deville it up by the break petal next to the firewall.
You can find several relay switches on your 1990 Cadillac Sedan Deville. Most relay switches will be in the fuse box. The relay switches will be in the third column of the fuse box.
Behind the glove box.
Its under the back bench seat on the passenger side.
Where is the fuse box on a 1987 cadillac sadan deville.
the fuse is next to the parking brake The relay is in the box under the hood near the wipers.
Inside the glove box there is a button you push. I think you got to have the ignition on for it to operate.
For most GM vehicles, the turn signal flashers are under the dash, just left of the steering column. There is usually an access door or some kind of panel that covers the fuse box where the flasher resides.
There is a flasher can under the dash on the drivers side or near the fuse box it unplugs easly for replacement
Its under the back seat. have to lift it up in the back and pull out towards the front of the car, your other fuse box is there as well.
it is in the fuse box under the hood directly above the A/C relay. In fact the A/C relay is exactly the same.
Remove the glove box,remove the dash. 4 nuts on instrument bezel,2 above the glove box & off it comes.Watch for front speaker wires & others