Recently acquired a 2004 S60R in trade for my S90, and it was mentioned the brake lights will occasionally stay on, which I've only had happen recently, i plan to probably get some LED bulbs to prevent running down the battery but if I can id like to fix it, the third brake light works properly and is not lit when the two lower ones are (I read that they're powered slightly differently) where do I look for this?

also i have a P0134 "bank 1 sensor 1 no activity detected" and the fuse is good so I'm assuming the sensor is likely bad? rear O2 is functioning as i just fixed the code with that and there's no leaks at all around the sensor and the wiring/insulation etc. look fine.

 

The 3rd brake light (10/19) is powered from the CEM, the other 2 from the REM. They are controlled with a relay (2/79) and a shunt (20/31 which I still don't understand what it does)

.LED bulbs will cause a permanent brake light out warning - unless you do additional stuff to just to have the cool look of a LED.

 

So i guess to use LED's id have to use a resistor like one would for a blinker to prevent hyperflashing. ill check the relay/shunt when i get a chance

 

I have found if the brake light is staying on on most cars there is an electric switch the brake petal hits. If it gets worn down or if there is a rubber grommet that hits the switch and it falls off it won't press the switch and your lights will just stay on. If it's a rubber pad missing you might be able to use a small bolt to press the switch.