Hyundai Repair: taillights on constantly, no brake lights, marker lamps, tail lamps

Question
I have a 02 accent. The othe day i went out and the taillights were on but the light switch was off. When I engaged the brake pedal there were no brake lights. My question is what would cause this?

Answer
The tail lamps and brake lamps are on separate circuits, so it would seem that there would need to be two separate failures for the tail lamps to be on and the brake lamps to not operate.  This leads me to ask whether we're sure it was really the tail lamps that were on and not the brake lamps.  If the brake lamps had been on for quite some time, they may have run the battery down to where they were so dim they appeared to be tail lamps.  The following should help you determine for certain (if there's any doubt) whether the brake lamps or tail lamps were on:

1.  The brake lamps should light up the lamp in the center.  If that lamp was on, it was the brake lamps that were illuminated.  If not, it's more likely it was the tail lamps, but the bulb could be burned out, too.

2.  The tail lamps are also wired with the front parking lamps, the marker lamps, and the license plate lamps.  If these lamps were on, we should be able to consider this confirmation that it was actually the tail lamps that were on.  If none of these lamps were on, we should be able to consider this confirmation that the brake lamps were on (since it would be very likely that *all* of those bulbs were burned out).

If we look at the scenario where it was actually the brake lamps that were on, it would be my speculation that the brake lamp switch was shorted or misadjusted, causing the brake lamps to stay on.  Thus, when the brake pedal was depressed, the rear lamps did not get any brighter.

If we look at the scenario where there are two failures, one with the tail lamps and one with the brake lamps, I'd be looking for the following:

1.  An open brake switch.  If the two wires for the brake switch (if you have a two wire switch) are jumpered, this should cause the brake lamps to come on.  If this occurs and the lamps do not come on when the pedal is depressed, the switch is defective.

2.  A short circuit causing the tail lamp relay to stay energized or a stuck closed tail lamp relay.  If either of these is the case, removing the tail lamp relay should cause the lamps to go out.  If it does, substitute another relay from the box that you know is working properly.  If the lamps stay out, the relay was defective.  If they come on again, the wire leading to the switch is somewhere shorted to the body of the car.