brake switch try some wd40 on it first if no help then replace it. by the way it is up where the brake pedal rests under the dash.
brake light switch would be most common cause
could be a bad alternator or battery
There is a switch just above the brake pedal that is called the brake stoplight switch. When the brake pedal is released, it stops the brake lights from illuminating. Check to make sure the switch is contacting the brake pedal stop where it should. A short term method of not killing the battery would be to unplug the connector to the switch and get a new one. It won't have brake lights when disconnected so I don't recommend driving with it like that. replace the broken switch
Those tail lights could be the brake lights you are seeing and that would be a faulty brake light switch or the brake light switch is out of adjustment.
this happened with my 94 sentra just before the alternator died... i would take it to a parts store and have them test the battery and alternator.
where is the fuel filter located would like to see a picture , 1990 Nissan Sentra sedan
If the brake lights stay on even when the car is off I would suggest checking the pedel itself. There should be a plastic/rubber plug that rests against the switch that controls the brake lights. If this plug falls out or becomes damaged then the pedel shaft never compresses the switch to an off position. Other than that you might want to look at a wiring diagram and trace the brake switch circuit to make sure there isn't a short in the circuit. I had this problem on an 87 Sentra years ago so I imagine Nissan hasn't changed the design in their cars all that much. Hope this helps.
Change the fuel filter.
brake switch ???
98 Nissan sentra only came with ga16de and sr20de, any ve motor would be considered a swap seeing that its a motor made strictly only in japan
fuse, bulbs
It's probably your Alternator that is going bad. That is if the battery and brake lights came on at the same time.