Hundai Accent 1999, back lights ( brake) - they light constantly

ABS means your brakes may not stop your car properly at high speeds and make the car wiggle and swerve.
I don't know what the code means but if I was you I have the brakes checked.
read more about the anti-lock brakes here,
https://en.wikipedia.org/wiki/Anti-lock_braking_system

By any chance did you find urethane button parts on the drivers floor mat?

Look under the dash at the brake pedal lever just below the pivot point for a small plate with a hole in it. Normally the hole has a white/yellow urethane (rubber) button in it that makes contact with the brake light switch turning the brake lights off. If this button is missing the brake lights will stay on all the time and run your battery down. If your brake lights have been on steady all this time they could burn out too. The bad part is that no one knows when you are braking and you could get into an accident and worse, found liable for not having your car in a safe operating condition resulting in a ticket and so on. While you might be able to find a substitute for the button, that could damage the brake light switch plunger tip making matters worse. The button from Hyundai is very cheap and a quick fix.

You need adjust the brake pedal with the switch, is possible to be too tight, need to loose it a little, if not, just change it, is easy.

May not be a light, may be a sensor or a blown bulb, not fuse. Pull cover off fuse panel. Panel should tell you fuse location. cehck owners manual if you have one or go to autozone.com and register with them. You can download info to help you out with problem.

Brake light switch on brake pedal needs to be adjusted until the light turn off.

Some smart car will shut down the engine if the oil presure is low. If you think it is the case then after you put the oil at correct level, it should start. Since it died while you were driving and you could not start after that, I think the problem is the crankshaft sensor. It is getting bad. Have it check out and replaced.

Is it just the Rear Window Light that stays on, or is the Rear Window Light and the brake lights located at the back/bumper of the car? If it is BOTH the Rear Window Light AND the brake lights at the rear of the car, then you likely have a faulty brake switch located at the brake pedal inside the car cabin. When the brake pedal is in the normal position, ie - you are not depressing the brake pedal, the arm of the brake pedal leading to the pedal with your foot pushes upon... this arm is applying constant pressure to the switch - with keeps your brake lights OFF. When you apply pressure to the brake pedal, it moves the brake arm away from the switch, which activates the circuit, and your brake lights turn on. If this switch is broken, your brake circuit thinks the brake pedal and arm are being pushed away from the switch, and your brake lights turn on. As you are aware, having the light on constantly can wear down your battery AND the heat from this constant light bulb of the brake light in the rear window can deform the shape of the red reflector in this rear window light housing. If, however, it is only the rear window light that stays on - then it is probably a loose or bad connection where this light plugs into the rest of the circuit in the trunk near the back seat. If this is the case, follow the wires from the rear window light assembly to the point where they plug into the rest of the circuit (inside the trunk) and unplug this wire set, clean the terminal ends, and plug them back together. ***WAIT, WAIT!!*** because you of the risk of touching the terminal ends together and blowing the circuit, if you also plan to clean the hot side, please remove the NEGATIVE battery terminal while cleaning (DO NOT USE WATER, just a wire brush or steel wool). After you are done cleaning and have the terminals reconnected, reconnect the negative battery terminal (you will also have to reset your radio stations and radio clock).

On some cars the bulb for the brake lights is separate than the tail lights. If not then check the fuse for the brake lights. It is typically separate from the tail lights. Also check for broken wires in the trunk area. These could be damaged from items in the trunk moving around.

the abs light comes on whenever the system detects a fault , when that fault no-longer is there the light will turn off , you should have a code set in your cars computers history . a competant mechanic should be able to get those codes for you to determine where to start diagnosing your abs Light issue .

1st check the easy things, that would be the brake fluid level. If it's low, the light will go on. Next check the emergency brake, if it's on slightly, the light can come on. Your fluid should be changed when u have a brake job done, the light wouldn't be on for that, only if there is a problem w/ the system. Check this out asap, as it can be unsafe to drive. If adding fluid to the proper level results in the light going out, make sure to check the level daily to make sure u don't have a leak in the system (and u can look under the car for signs of a leak-drips stains puddles). As your brakes wear down, it is normal to have to add fluid, but only a small amount maybe a couple of times between brake jobs. If u have the brakes done in the future, have them flush out the brake system. This is overlooked most of the time, and can result in problems down the road w/ corrosion of calipers and brake cylinders, which lead to premature wear on the brake pads and shoes. Let me know how u make out.