QUOTE(Maizie @ Dec 12 2011, 03:26 PM)

So last week - on a dark, wet night - my car decided to have the back lights stop working. Not good.
I spoke to my mechanic, and at the weekend took the car over to him for fixing. He was bemused at what would affect the back lights but not the front side-lights (as they live on the same circuit, all coming on when you put the headlights on "one click"), but me dropping the car over gave him the chance for a full investigation.
It turns out, both bulbs had gone

We did actually think of that after I'd dropped it off. My husband said "It's too much of a co-incidence for both bulbs to have gone at the same time", and then I realised (and said) that one could have gone
months ago, and how would I know? And then the second one goes, and only then do people behind you in the car flash their lights manically at you! And it turns out that's probably exactly what happened!

But, rather than feeling entirely stupid over that, I am happy because my car battery was replaced under warranty! Since the weather changed, and I've been driving much less with work changes, it's taken a few 'turning overs' to get it started. Well, it turns out that wasn't due to the weather or lack of driving. He charged the battery up, but it still wasn't playing nice, so as it is new enough, he swapped it for a new new one under the warranty.
So in half an hour I'll be off to pick up my correctly lit and fully charged car

You may be interested to know that light bulbs in cars often do fail in pairs. There is a good reason for this:
Firslty, similar bulbs from the same manufacturer will have a similar design life.
Secondly, a pair of stop, tail or headlamp bulbs will operate for exactly the same number of hours.
Thirdly, and crucially, when one fails, the voltage applied to the other bulb in the pair will increase slightly; so if it is nearly at the end of its life the extra voltage may just be enough to finish it off!
In the case of stop lamps, these are often applied when the engine has been running at speed, so the voltage will be higher than at tickover.
I had a stop light bulb fail on my car. (I knew because the computer thingumy told me.) I replaced it the same day, but the other one failed two days later.
So, if you need to replace a bulb buy a pair, and check the other one to see if it looks blackened. If so, replace it. It's safer, and cheaper than a fixed penalty payment!
What I cannot understand is the number of people who drive around in cars with only one headlamp working. If you do, just hope that the Lithuanian driver of the 40 tonne truck coming the other way doesn't assume that you car is a moped, and so uses the opportunity to overtake.
SB