Headlights go off briefly at gear changes

[simboc2004]

I have had an issue over the winter that, every time I change gear my headlights appear to go off very, very briefly. I am assuming this is due to the brief rev drop (it's a manual gearbox). Has anyone else had this? I am thinking it's either a failing battery (although I have charged it fully and it still does it) or failing alternator... Any thoughts? I had begun to think I was imagining it...

[tommyweaves]

Originally Posted by simboc2004

I have had an issue over the winter that, every time I change gear my headlights appear to go off very, very briefly. I am assuming this is due to the brief rev drop (it's a manual gearbox). Has anyone else had this? I am thinking it's either a failing battery (although I have charged it fully and it still does it) or failing alternator... Any thoughts? I had begun to think I was imagining it...

I'm pretty sure my D3 manual does something similar. Not off, but very slightly dimmed for a brief moment. It's done it for years, and is only noticeable in the winter. The car is still on its original battery (getting tired now) and alternator, and it was doing this thing well over 5 years ago.

[simboc2004]

I'll work on the basis of "if it ain't broke, don't fix it" then... I just find it a bit distracting...

[Stu B]

I've cured similar on older, less electronically complex cars by simply swapping the voltage regular and/or brush packs in the back of the alternator before. Might still apply as I would think it's more related to the alternator than battery condition once the engine is running?

Have you got a multimeter? Quite easy to test the battery and alternator behaviour if so?

[simboc2004]

Yes, I have got a multimeter, but, as usual, the issue doesn't bother me when the days are long enough and warm enough to do the work... Thanks for the pointers, though. I might try swapping out the alternator if it gets worse.