Brake .lights

[ivor4781]

i have a 2014 kas rio and its keep blowing rear brakes light every 2/3 months either one side or last time both sides,easy and cheap to replace but on all my other cars they have lasted years

[bhg481]

Bulbs blowing often indicates a fault with the alternator. It could be that there is a problem with the regulator and the output voltage is too high. Check it with a voltmeter; with the engine running and the headlights on the voltage shouldn't be more than about 14.5.
Bulbs tend to fail at the moment they are switched on - they take more current at that point because the element is cold. Brake lights are switched on and off more frequently than any of the other bulbs in the car, so these will be the ones most likely to fail.

[Quoi]

No factual basis from me for this but I was told that if one bulb goes then replace both at the same time.
Worked for the Volvo I had at the time.

[bhg481]

The only argument for that Quoi is that both bulbs are the same age and have been switched on the same number of times so, if one blows, the other is likely to go soon.

[Quoi]

As an ignoramus - I think they were trying to tell me that the remaining bulb would be subject to more voltage because the other one had failed - something to do with the 'bulb failure' circuitry in the volvo at the time.
Probably just trying to flog 2 bulbs not one now I think about it.

[bhg481]

It's not a totally silly thing to do. Apart from the convenience of only having to mess with the lights once instead of twice, if you look at a bulb which has been in the car for a long time you will see that the glass has blackened due to the tungsten from the filament evaporating and condensing on it. I've been known to change bulbs simply because of this not because the bulb has blown.