The fuse for the backup lights on a 1990 Jeep Cherokee Laredo is located in the
underhood fuse block. It's not always clearly labeled, so you may need to consult your owner's manual for the correct fuse location and amperage. The manual will have a diagram of the fuse box showing what each fuse controls.
If you don't have the owner's manual, you can often find a PDF version online by searching "[your year] Jeep Cherokee Laredo owner's manual".
