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Discussion Starter · #1 ·
I'm currently having an issue with Adaptive High Beam Assist on my GLA whereby when driving on any of the narrow, twisty roads where I live in North Wales, with no other traffic or lighting of any kind nearby, the Adaptive High Beam Assist frequently decides to switch to very-low beam at the very moment one needs high-beam the most: on the entry to tight bends. It also rarely switches to full-beam at all on single-track roads, yet when driving on 'normal' suburban A/B roads or motorways, everything works as expected. The car has passed all its diagnostic checks so I am about to escalate this issue with MB. Before I do, has anyone else with the automated lighting package noticed similar behaviour from their GLA?

PS: in all other respects the GLA works perfectly.
 

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Well....
I picked up my new GLA 45 on Friday and now I am waiting for a replacement drivers side head light assembly. I am a bit disappointed with quality control. This should have been picked up by both the factory and the dealership....
 

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It keeps on displaying "Intelligent Lighting system inoperative" along with "High Beam inoperative".
They initially updated the car's firmware but the problem persisted.
Today, they said I need a new part ....
 

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Discussion Starter · #5 ·
Oh, right, that seems like a definite snag then, as opposed to a possible bug through specific circumstances i.e. driving on twisty narrow roads. These new cars are packed with extremely complex technology so it's no surprise that some are going to have initial glitches as new components heat up and are used in anger. I wouldn't worry too much about it as MB will sort it all out with a smile, I'm sure. I've owned Mercs since 1986 and can count on one hand the problems I've had in all that time :)
 

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To be honest, I cannot fault my local dealership over the response; they have been very accommodating.
I've just finished driving a CLS for the past 3 years; I go though a "heart" vs "head" car decision every few years. Choosing a diesel is my concept of a "head" car (ie I think about the fuel economy). The GLA 45 is very much a "heart" car

I am following the "running in" guide so it will be a few miles before I can introduce it to the back roads around me.
North Wales eh? I have fond memories of some of the roads around there... Climbing the Horseshoe Pass in a Reliant Robin with my mother at the wheel... she never successfully learnt to drive.
 

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Discussion Starter · #7 ·
I live very close to the Horseshoe Pass; in fact it was on the 'horseshoe' bends, on the way back from picking up the car, that my particular problem with the lights first showed itself. Fortunately we know the road very well, otherwise we might have ended up in the bank!
 

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Living in Mid Wales I have experienced the same problem when I get close to home along narrow and twisty lanes, it is related to the speed of the car and have assumed that it is how the MB guys have decided to ensure dipped lighting in towns i.e. below 35 mph.
I have developed the habit of turning the light switch to manual as I get onto the slower sections of road to keep the main beam activated.
The delay in dipping has also irritated oncoming drivers where I would normally have dipped just before they appear around the apex of the bend but the AHB needs to 'see' their lights before dipping.
A great idea but dissappointing on country roads.
 

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Discussion Starter · #9 ·
Poolflyer said:
Living in Mid Wales I have experienced the same problem when I get close to home along narrow and twisty lanes, it is related to the speed of the car and have assumed that it is how the MB guys have decided to ensure dipped lighting in towns i.e. below 35 mph.
Is this a known fact or an assumption based on observation and/or speculation? I suspected that it might be speed-related, so I gritted my teeth and raced into the darkness down a narrow road that I know well. It made no difference.

I am waiting to see if anyone else has this problem before escalating the issue with MB, so I'm interested to know your findings.
 

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Discussion Starter · #11 ·
On reading the manual in more depth I have discovered that, given no other road users or street lighting, the Adaptive High Beam Assist enables high beam when the vehicle eceeds 34mph, and disables it when the vehicle drops below 28mph. Maybe this would explain the sudden loss of light when about to take a sharp bend on the Horseshoe Pass, as in breaking for the turn-in. Maybe when I put my foot down in the pitch-black, I did not quite hit 34mph, although I'm sure I did, and some. I will have to do some more tests to see if this might explain it, but either way, I think it is a safety issue and with tell MB so (we nearly hit the bank!). It seems ridiculous to me to set these thresholds at those speeds. What is wrong with bringing the lights up at 15mph, or dropping them down at 5mph? Why pick such high speeds? ...any ideas what I might be missing, anyone?
 

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Discussion Starter · #12 ·
Update: I'll be checking out my speed theory tomorrow but in the meantime I've just had a call from the salesman who sold me my GLA. He explained that he was driving a GLA 45 down some unlit roads when he suddenly lost full-beam on a bend and nearly ended up in a ditch! Needless to say, he is taking my complaint fairly seriously now, and will be escalating the issue once I have reported back with my findings tomorrow night.
 

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Interesting comments as for the first time yesterday I drove at night (GLA 45 with intelligent lighting) and was a little disappointed in it. In auto mode I had to select main beam on unlit narrow country roads, and noticed a delay in activation, and deselecting was the same. I have not gone back to manual mode yet but don't expect any issues there. However, I would say the lighting is very good in terms of coverage and intensity, just found the auto lights a little weird! Would be interested to see what MB say to your issues.
 

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Discussion Starter · #14 ·
Last night I was able to confirm that the GLA's 'intelligent' lights do indeed switch from full-beam to dipped-beam in accordance with the manual i.e. they switch to full-beam at 34mph, and dip at 28mph (assuming an unlit road with no other traffic). Thus, if one travels down unlit roads in the countryside with the lights on full-beam, then one brakes to take a sharp bend, at the very moment that one needs the lights on full-beam to see where the road is going, the car's speed drops to 28mph and the lights dip in an instant, plunging the way ahead into total darkness ...be warned!

In my humble opinion, MB should alter this behaviour to speed thresholds of around 5 and 15mph or even less, so I am raising the issue with MB. If anyone else has a problem with this questionable behaviour, I suggest that you also raise your concerns with MB because presumably, the more people shout about it, the more likely they'll take it seriously (not that they haven't taken me seriously yet).

Edited by: roytheboy
 

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Discussion Starter · #15 ·
Update: my GLA MB salesman doesn't seem to be getting very far with this issue of the full-beam lights dropping just when you need them most i.e. as you brake for a sharp, unlit bend, so I have now contacted MB customer services myself and have stressed that I want this issue looked into. They have raised a 'tech case' and have promised to investigate. In the meantime, be aware that if your speed drops below 28mph as you approach a sharp bend in 'auto lights' mode, you *WILL* suddenly lose your full beam lights
 

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Since most of these functions are controlled by software the solution should be both easy and quick...It strikes me that unless it detects lights coming towards you, there's no need to dip.
That said, I presume that if it sees its own reflection it will also dip? Does this still happen if you switch from Auto to "Always On"?
 

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Discussion Starter · #17 ·
Yes, this is what I told MB. I said that unless there was a good reason not to, that the raise/dip speeds should be lowered to something like 5 and 10mph; not 28 and 36mph. It is, as you say, a software issue, that should be correctable at the next service for most people. This issue only affects the 'auto' function, not the manual mode.
 

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Yesterday, I was taken on an interesting route home.
The M1 was busy, and the nice lady in the Sat Nav suggested a different route, so I followed her advice (mistake #1)
No sooner had I turned off the motorway she started giving me traffic updates... the UK was grinding to a halt. At various times she suggested making a U turn, eventually I ignored her and followed my instincts.
My route eventually took me up the A1 and towards the A47.
I agree with you about the head lights; gosh, are they not slow to go on to full beam when in auto mode?... especially when one's right foot is pressing hard....
It wasn't long before I switched to "manual" mode, at least this way, the main beam comes on when I want it to...
I think I should send an email to MB......
 

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Discussion Starter · #19 ·
I've heard nothing back from MB yet, so it probably wouldn't hurt for someone else to be adding their voice to my concerns. To be clear though, I am perfectly happy with the normal automatic operation of the full-beam; it's just the speed-related overrides that I have a problem with.
 

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I too share your concerns, finding that on "auto" the main beam does not react quickly enough (if at all) to dark roads with no other traffic. I too resort to switching to manual override. I will try the "speed related theory" next time I'm out in the dark as I usually "press on a bit" 😊😊😊
 
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