260 Headlights

I have 2 distinct brightnesses at both the headlights & all the instrument
lights, high beam & low, which doesn't seem dependent on engine revs, road
roughness etc... just brightens for a short while then goes back to
dull-ish. Hard to say which brightness is normal, the instruments always
seem dull in daylight but that could be because it's hard to see anyway.
Does anyone have any suggestions to check before I look at the voltage reg
and alternator? It has had a battery collapse recently, looked like it was
due to go. Fuel pump relay failed almost simultaneously. Thanks in advance
for any suggestions.

 

My first thought is for the alternator, especially the brushes. In most
systems, the alternator light doesn't come on when the brushes fail.

Mike

 

It will if they fail completely, but chances are they're worn.

 

Based on how long the lights stay bright for, it would be charging for a
minimal time - maybe 1/10th running time. The alt light works but never
comes on driving and there doesn't seem to be a problem charging. There's no
flickering & the 2 brightnesses seem consistent, not a varying range. Could
it be the (separate) regulator?

 

I'd suggest you start by looking at the grounds for the headlight. If
one is bad, that side will ground through the high beam filaments to the
ground on the other side. My suggestion - start on the side where the
battery is.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

Ah I didn't realise they had earths, I thought they would have 2 wires back
to some dark place under the dash. That's what I was looking for, the easy
fix things first.