I noticed that my tail lights stay on even with no keys in the ignition, but that my brake lights have stopped working. Also, my left turn signal blinks double speed.
When I remove the fuse for the brake lights then the tail lights go off, but if I turn the light switch on, the tail lights will come on. When the brake lights fuse is removed the signal blinks at normal speed. I also noticed that if I play with the tail light wire I can make the turn signal go on ( but not blink ), and the tail light off, or visa versa.
From a wiring diagram I see the tail light and brake light share a ground wire:
Could it be that the tail lights and brake lights are shorted together?
It's a 99 Nissan Almera 1.6 GX
EDIT July 8th, 2016
I've come back to this problem and found that, indeed the brake switch doesn't seem to be making contact, and if I remove the switch and depress the button on it manually, the tail lights go out. But of course the question I have to figure out is why is the brake switch operating the tail lights instead of the brake lights!
Ok, so I removed the brake light fuse, disconnected the brake light switch connector and took a length of lamp cord to test continuity with my multimeter. I'm pretty sure I'm doing the continuity tests correctly. There was continuity from the switch connector to the brake lights, and from the switch connector to the tail lights. Strangely, there was no continuity between the brake light fuse pin and the brake lights. However, there was power on the other brake fuse pin even though the brake switch was disconnected, and the keys were in my pocket. I bridged from the brake fuse pin that had power on it to the brake wire and one of the brake lights lit up.
So this doesn't make a lot of sense to me. I'm going to have to sit and think about this a bit.
EDIT July 20th, 2016
OK, so it really was just the rubber stopper ( part# 46584-S0100 ) for the break switch that had apparently disintegrated. I got confused because the car has a combination tail / break light. If the tail lights are already on, and you push the break in, it just makes the tail lights brighter and turns on a high level break light strip on the trunk. What I thought was part of the break lights system is actually a fog light, and that's why there is only a bulb in the left side housing and not one in the right side housing.
Why there is electrical continuity between the break switch and the fog light I don't understand, but that's a separate question.
Here's a picture of my fix:
I just put a nut in between the brake pedal and the mounting point for the switch, and then screwed the bolt in from the back to hold it in place. I should really probably add another nut on the opposite side to lock it in place, but I'm a bit tired of this problem at this point.