So this past week I have kept getting the "left brake light" warning sign-however car is only a few months old and I checked with someone that indeed the brake lights are working fine even when the message is up. It usually comes up and goes away next restart.

Is this a computer code issue or is that how the brake lights work-they have some back-up or something before they totally go? BUt I would guess the warning light would not go off and would stay on if it were a true problem.

 

I would guess it's computer related... I've had the same for the left taillight and also most recently for the left reverse light. all was ok on the next restart.

 

From my years in the autobody industry(few years ago) I do know that most of these "you have a light out" systems work by monitoring voltage over the wire. If your bulb is getting ready to go or if there is corrosion on the wire, it can cause drop in voltage and trigger the warning. I found that it is best to replace both bulbs in pairs if the problem does not disappear. My X5 had the same issue. Replaced the bulb that was out and it still said that I had a brake light out. Did not disappear until i replaced the corresponding bulb on the other side. I hope this helps.

 

The way this work on our car is the LCM send out pulses of power to check the bulbs every so often. So you must have a faulty LCM or computer.

 

My buddy's old M3 used to have that problem all the time. It was moisture and corrosion related though. Purely a layer 1 issue.

 

Thanks guys-I can live with an occasional warning indicator-would be a pain if it was on all the time. I swear the more technology we have the mroe to go wrong. Geez I realized how much crap these cars have technology wise-and there is just NO way in hell I would ever own one not under warrant- can you imagine repairs on some of the sophisticated technology in there. The days of just needing brakes, alternator and a few other things are gone.