F25 Headlamp issue

[Johne]

Something very strange happened tonight. Took my car out after dark and I thought that the dipped beam was poor so I pulled over and switched the lights off and then back on again. During this process the lights were momentarily bright and then went off again. I think that the main beams are working but when I look at the front of the car the two inboard lights just have the side light function working. No warnings on the dash so any ideas as to what it might be.

The car has adaptive lights and they are also xenons. I am sure that the functions are all intact so maybe its a faulty light switch or relay or something else

[X5Sport]

Not all BMWs actually have lights in the inboard pair. Those are just for show until you get to certain 3-series and above. Worth checking that you actually have proper lamps in them. My F46 Gran Tourer and X6 inboard pairs are angel eyes only.

[Johne]

Thank you. There is definitely something amiss because the lights are no where near as bright as they were and when I switch them off and back on again they are momentarily as bright as they were.

I dont think that the dipped beams are working at all

[X5Sport]

If you have Xenon lamps then it’s just a shutter that defines the beam, the lamp is the same . Unlikely both of the adaptive units would fail at the same time. It could be the bulbs themselves are going, or a bad earth, though again both together is odd and the lamps last for years.

What happens if you use Manual lights on rather than Auto (you may have tried it)? Can you see the pattern when you point the car at a wall or garage door? Does it change when you select High Beam?

Does the beam ‘rise and fall’ as the auto-levelling cycles on first switch on? I did have a car where the dip beam got stuck at its lowest point in the levelling cycle and left me with a dip beam about 10’ in front of the car - which wasn’t much use. That was a sensor fault thinking the car boot was fully laden even though it was empty!

Not sure what else to suggest.

[Johne]

Thank you. I am beginning to question my sanity now because I read elsewhere that the inboard halo lights are just that and dont have the dipped beam. When it goes darker I will do as you suggest and try the lights against the garage door and then come back on here with the outcome. They were certainly very dim and I am not sure that the main beam is as good as it was so does the same bulb do both functions

[X5Sport]

On many BMWs yes one lamp is used for both (also known as Bi-Xenon) with an electrically driven shutter that masks the high beam pattern until required. The inner projector is a fake for cosmetic purposes and may be used to hold the older filament type angel eyes bulb only (E70/71).

Why on Earth BMW spent all that effort on a fake cosmetic look and then failed to put a proper bulb in will only be known by the bean counters!

[Johne]

Ok thank you

I have just started it up and the lights certainly moved to self adjust but the light given off is very yellow and not bright at all. There is a definate cut off against the garage door and the adaptive part is working when I put the lights onto auto dip mode. When the wheel is turned the front fog also lights up, dont know why though because the light given out by the fog is poor.

So this leads me to think that both systems are working but not as they should in terms of brightness so does this mean bulbs and or a ballast module as well@

Most certainly when I started the car up pointing towards the garage and turned the lights off and then put them into manual mode and back on again the initial light, fraction of a second probably, was very bright and white.

[X5Sport]

The first moment is the ‘flash’ as the arc strikes (hence the very high voltage ballast needed to generate up to 25kV!) before the lamps warm up (and then runs at 85V). HIDs (the proper name) are arc lights.

If they are starting to fail then the colour is generally pink to violet rather than yellow, and a ballast fault usually means no light as the arc never strikes, or severe flickering. OEM bulbs are around 4,300°K with the whiter LEDs being 5,500°K. You can get whiter HIDs nearer LED colours and if you go down that route then beware of Chinese knock off bulbs. They are cheap for a reason - bad arc position and poor focus leading to glare.

I have replaced the OEM bulbs with Osram Xenarc Nightbreaker Laser bulbs on my X6 which are very slightly yellow compared to the excellent LEDs on my Gran Tourer. They are much brighter than the OEM fitted Osram Xenarcs that the car came with with the same 35W rating.

[Johne]

I am sure that mine were much brighter and with a white light only a few days ago and I seem to remember the flash not fading back so much. Looks as though I will have to fork out for some new bulbs and hope that fixes the problem because the ballast module looks difficult to get at and might need coding into the car so probably a professional job.

[X5Sport]

Is your battery OK? Bit of a shot in the dark (no pun intended) but I’m wondering if the volts are down and whether that’s a potential source of the change? There aren’t a lot of other things that I can think of that would affect both lamps simultaneously.

Assuming that you have an AGM battery, you should be seeing about 14.4V (13.8V if a conventional wet battery) with the engine running and at least 12.5V after 4 hours since last use with the car asleep (using the under bonnet jump points to measure).

After that it may be a case of getting an error code check done to see if anything has been recorded.

[Johne]

As far as I am aware the battery is fine. Never had a high drainage warning even when I have been messing around with things on the car. Next Monday my independent garage opens so I will call him and see if he can check for error codes.

As a matter of interest is it safe to upgrade the bulbs in terms of over heating

[X5Sport]

As long as you use the same power rating (35W) no issue. If you want to fit 55W lamps then you need to change the ballasts as well. Higher wattage means more starting voltage and current is needed. The bulbs I used are still 35W but produce higher lumens (brightness) by using a different gas mix in the plasma chamber and possibly by running at a higher pressure. I’m not sure an extra 20W will melt anything though. No one who did it on their E53s ever reported molten plastics in the headlights.

If you do decide to fit different lamps then make sure you have eye protection on and I wore surgical gloves in case I touched the glass accidentally. The lamps are very high pressure so need careful handling - though given a BMW ‘mechanic’ can change them they aren’t that delicate .

[Johne]

Thank you. I may well upgrade but stick with 35w bulbs because taking the ballast thing out looks a bit onerous. On Monday I will get a quick diagnostic done just to be sure

[StuBeeDoo]

The inner projector is a fake for cosmetic purposes

Blige!! I just had a close financial shave. I never knew BMW did ^^^ that. I was about to drop over £250 on 4x Osram Xenarc Nightbreakers. Before I left for work this morning, I put the mainbeam on and sure enough, only the outer projectors are lit. Only 2x new bulbs needed, £125+ saved.

Mind, I can't help feeling slightly conned by the fakery.

[Johne]

This has raised its ugly and probably expensive head again.

I dont think its the bulbs because whilst driving to Penmachno for the Cambrian rally last Friday night both my passenger and I thought that the light distribution was much to high. There is an obvious cut off for both lights and they do certainly move when the car is started and indeed if the "A" is lit up then they move sideways as well and the lower front fog comes on as well.

I was getting warning flashes from oncoming drivers even when I was on dipped beam and so I am beginning to wonder if there is some sort of levelling kit that simply isn't working. Any thoughts