A very odd thing happened to me when I was driving late at night on Tuesday. Three HGVs flashed their headlights at me, but no cars. I definitely did not drive on full beam into oncoming traffic on three occasions. When I looked at the headlights they seemed okay though quite bright as the bulbs have recently been replaced. What set of circumstances could affect an HGV driver but not a car driver? Is it possible there is a stray beam pointing upwards? I think I'll take it to the MOT station and ask him to check.
Dipped headlights
Aug 06, 2026
Last reply: 7 hours ago
10 Replies
Although I've never heard of it and it /shouldn't/ be possible, have the bulbs been put in upside-down, so that when on "dipped" it's the complete opposite?
My newish car has LED headights, where the lights are split into multiple zones and when put into "auto dipping" mode it can dip the zones independently.
I was sceptical about using the autodip feature, but I did test it out one night, it feels very odd leaving full beam on, and not worrying about oncoming traffic, but you can see it adjusting the lights and no cars at all flashed me for it.
However I do remember when I was at the bottom of a hill, and a lorry was coming down the hill towards me, it flashed me at quite a long distance, so probably something about the raised cab height can mean lorries notice high-beams more than cars? I haven't used the auto-dip much (at all?) since the night I tested it ...
That's an interesting thought. Also, the side light is in the the same unit above the headlight so I wondered if it could be misaligned. Can I easily check [both possibilities] or should this be a trip to the installer?
Is the side light one of those bright daylight-running leds? Perhaps it is misaligned.
Not sure how I'd check, other than at night put the main beam on a couple of metres from a wall, and put a mark where the centre of the beam is on the wall. Then switch to dipped beam and repeat. If it's above the main beam mark /something/ is wrong. It might require a trip to the dealer if it needs adjusting. However, my Jazz has a control on the dash whereby if you've got a heavy weight in the back you can turn a knob so the headlight points further down, counteracting the tendency of the back to be lower down and the front higher up.
Most cars tend to be auto-levelling now, I believe it's mandatory (along with headlight washers) above a certain brightness?
If you park on the level and shine your dipped headlights at a wall or your garage door you should be able to see the point of intersection of the two linear cut-offs in the beam, one rising off to the left (the part of the beam that illuminates signs to your left) and the other falling less steeply to the right (to keep your beam out of the eyes of oncoming drivers). That point of intersection should be pretty much at the same height as your headlamps and straight ahead.
If you get that pattern, the bulb is not in upside down!
nib
Not mandatory, but they must operate correctly: "Vehicles with high intensity discharge (HID) or LED dipped beam headlamps may be fitted with a suspension or headlamp self-levelling system. If these systems have been fitted, they must work." (
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There seems to be a lot more involved with headlamp beams. See
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. It also includes requirements for dipped beams.
2008 technology - Nissan Micra. Could the garage have fitted unsuitable bulbs (LED in place of halogen)?
can you see any (E) markings on them?
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