Main beam duller than dipped headlights

[timski]

Hi there,

Suddenly my main beam is duller than my dipped beam. They are so dull a pair of candles would be better!

Also the high beam won't stay on. I have to hold it on. This seems to have occurred at the same time although I don't use high beam often so can't be 100% sure.

Could this kind of problem be related to the earth crowns by the fuse box?

Oh and just to be sure dipped headlights are first click oh the switch and main beam second click?

Thanks
Tim

[itchyfeet]

more likely to be the stalk

[a1winchester]

1st click on the dash switch = side lights, 2nd click = headlights. Change from main beam to dipped and back by pulling the stalk on the stearing column.
When on side lights, pulling on the stalk operates the main beam headlight flasher. That's why you have to hold it on.

[timski]

Ok just rechecked and high beam does stay on when I've got main beam selected on the dash switch so that appears to be working ok.

Any ideas why dipped beam would be brighter than main beam?
Thanks,
Tim.

[timski]

Mmm was just checking again and had a closer look at the bulbs inside the main headlight. When the dipped beam was on the little side bulbs inside were lighting up and it looked like the main bulb was glowing slightly too. When I switched to main beam the main bulb stopped glowing completely and just the little side bulbs remained on. I continued testing and then suddenly main beam is working again. So it's an intermittent problem of some kind.

[a1winchester]

The plot thickens!
Presumably you have the twin square headlights as you have a late '91 model.

[timski]

Yes that's right.

Am I right in assuming the smaller of the two square ones only come on with high beam? I have never paid much attention as there just worked.

Thanks
Tim

[a1winchester]

The inner pair are main beam, the outer pair dipped headlights.
The outer, dipped lights stay on when the main beams are turned on.

[timski]

The inner pair are main beam, the outer pair dipped headlights.
The outer, dipped lights stay on when the main beams are turned on.

Are you talking about the bulbs inside the larger of the twin square lights?

Thanks,
Tim

[a1winchester]

The outer rectangular lamps contain 2 bulbs, the dipped headlights and the small parking (side) lights.
The inner (square) lamps contain a single main beam bulb.

[clift_d]

It's always worth checking the earth crowns first as that's an easy fix. There are plenty of posts on here about what to do.

[syncroandy]

This is incorrect, the H4 bulb used in the main T3 headlight (in EU models) has two filaments, one provides the dipped beam, the other provides the main beam, there's a second, small sidelight bulb. The inner lamp unit has an H3 single filament bulb, which is used to supplement the main beam in the outer lamp unit.

The outer rectangular lamps contain 2 bulbs, the dipped headlights and the small parking (side) lights.
The inner (square) lamps contain a single main beam bulb.

[a1winchester]

Thanks for that - I had better check my bulbs then - looks like the H4 main beam fillaments may have both blown (And it's just got through it's MOT like that!)

Update - Bulbs are ok. All working as described - headlights in the outer rectangular lamp are on all the time, but have 2 filaments - dipped / main, and the inner square main beams only come on for main beam.

I think I must have been mistaking the outer light for the side light when I looked at it yesterday. - not easy to see in sunlight.

So apologies all round for a misleading post and thanks for the correction, Syncroandy.

[syncroandy]

The GB-specific dim-dip feature puts a reduced current (courtesy of a dropper resistor) through the the dipped beam filament when the lights are on.