Ford Focus-Headlamps blowing

[Elroy Blue]

Bought an 05 Focus for 'er indoors a few weeks ago. She turned the headlamps on a couple of nights ago and they both went out. All the other lights worked. Checked the fuse and that was ok, so took it back to the dealer.

After about 45mins they came back and said both bulbs had blown. They replaced them and said 'everything else seems ok'. Now the odds of both bulbs deciding to fail at exactly the same moment is about the same as seeing the Titanic floating down the Rivere Severn. The bulbs blowing is a symptom of something, rather than the cause.

Any electrical whizzes that can give me an idea. The warranty only lasts three months and I don't want to find a more serious problem after it's ran out.

[AB]

It happened all the time on my old Focus, I was forever changing bulbs.

Same is happening to my bro who also drives a Focus.

[Elroy Blue]

Any idea what the cause is?

[Zad]

Ever noticed the lights going brighter as you rev the engine?

[zetec]

One bulb blows, too much current to other bulb so that blows also? Well thats what I was told, would also explain why the fuse didn't blow?

[Elroy Blue]

Zad said:

Ever noticed the lights going brighter as you rev the engine?

No, the lights stay the same regardless of revs.

[NHK244V]

I'd be checking the alternator output, i get a lot of conects in with alt/bulb/wiring issues, they are based on the focus so i assume the same known problems exsist IE alt control looms chaffing through in various places, there's even a factory made repair loom for under a score to solve the issue, IF that is the problem ?

[Jonny_]

A mate of mine runs an 05 Focus and has the same problem. He goes through more bulbs than Blackpool Illuminations. Voltage on his battery looked OK (14.1v when ticking over, no change when revs increased), so must be something intermittent.

[Elroy Blue]

Hasn't done it since, so just keeping our fingers crossed at the mo.

[HellDiver]

Elroy Blue said:

Now the odds of both bulbs deciding to fail at exactly the same moment is about the same as seeing the Titanic floating down the Rivere Severn.

Actually, chances of both bulbs blowing at the same time are quite high. Headlight bulbs are precision devices - the filaments are identical, the amount of gas in the glass envelope is identical, the glass is identical. Why wouldn't they both blow at similar times?

Every car I've had has needed a second bulb within days of the first one blowing - now I just replace both as matter of course.

[Elroy Blue]

'Similar' times is very different from 'exactly' the same moment. Something occurred that caused them to blow.

Hasn't happened again so fingers crossed it was a one off.