Mercedes A Class - LED Lighting and the MOT
Discussion
Hello all......
Just thought i'd share with you some of the shambolic happenings i've encountered over the last month whilst trying to get my run of the mill A-Class through its MOT.
Car in question is a 64 plate A220 CDi. Being the AMG-Line model, its a few nice to haves on it - one of which is the upgraded lighting option with xenons up front and LED tail lights.
As i'm sure you'll agree, not exactly a rare car by any stretch of the imagination.
Bought the car as approved used from a Mercedes dealer. Part of the 'approved used' package ensures that your car will pass its first MOT in your ownership or Mercedes will cover the costs of anything needed to make that so (dare say there are a few exclusions there in terms of thigns like tyres and whatnot but, whatever, thats not relevant here).
Car's mot was due to expire mid-December, and having been in to Mercedes themselves for a major service just a couple of weeks prior, I put the car in for its MOT at my local station expecting nothing other than a pass......... however, to my surprise, i returned to collect my car a couple of hours later to be told it had failed.
Failure reason was listed as the following:
"Offside Rear Rear fog lamp adversely affected by the operation of another lamp brake light more than 50% of lights(led) extinguish when fog lamp switched on (4.5.4 (b))"
Basically, what this relates to is the way in which the rear lamp works. The sidelights and brake lights operate in a large back to front C shape pattern, made up of 27 different LED bulbs. Directly beneath this C shape lives the fog light which is positioned just under the bottom edge.
The side lights work. All 27 LED's come on exactly as you'd expect. Apply the brake and indeed all 27 LED's come on for the brake as well. Great. No problems there.
However, whilst holding your foot on the brake - if you then switch on the rear fog light - a portion of the brake light LED's go out. In fact, of the 27 brake light LED's, 15 go out and 12 are left illuminated whilst the rear fog light is on.
And for this reason, the tester has deemed this to be a fail.
So....... i get on the phone to Mercedes and get the car booked in with them to resolve the issue. They decide that they are going to order in a new rear light assembly for the car. So they get hold of the light and try the new unit only to find that the new light does exactly the same as the last one did.
They then proceed to do some digging about and come back to me after having the car for 4 days with the conclusion that the lamp is in fact designe to work that way and is working 100% correctly. Quite why it took them so long to figure this out and why it wasnt the very first thing they checked when the car went in I have no idea. Anyhow, they return my car to me complete with an extract from a technical document from Mercedes confirming that this is how the lamp should work.
Great, I think. I'll get back to the MOT station and get this resolved and car tested and passed and that'll be the end of it. Or so I thought.
Back to the MOT Station, armed with my technical information from Mercedes........ 'Nope. Cant accept that. Regardless of what Mercedes say, this doesnt meet the DVSA standard and i wont pass it till it does'.
So. Stalemate. And from this point, my only option left is to either pay someone else to MOT the car (Mercedes at this point had already confirmed they would pass the car if i took it to them), or take up the result of the test by means of a formal appeal.
In hindsight now i suspect I should have just taken the hit and let someone else MOT it - however, given that all testers are working to the same rules, if its a pass in the eyes or Mercedes, then its a pass at the station i took it to - or, vice versa, if it really IS a fail, then Mercedes cant / shouldnt pass it either.
Regardless, i decided i shouldnt be having to pay a second fee for this fi the car is in fact pass worthy - so decided to take up the appeal process....... which is where we're at now, a full month after the original test. The guy from the DVSA came out tto look at the car, took some photos and information from me and its now in their hands.
The whole thing has been absolutely mind boggling. Having spent most of ym adult life messing about with cars and being around them - this is the most shambolic experience i've ever had with regards to an MOT.
The thing which flabergasts me the most is that this isnt a 'new' car. This is this very car's third MOT from new. There are thousands of other exactly like it on the road - its certainly not rare thats for sure. How on earth has this not been flagged up before now if it is a design flaw with the lamp?!?
It gets even better when you delve in to the legislation which deals with the requirements of getting E-Approval on such lamp units which dictate that a fog light cannot be any closer than 100mm from a brake light - which to me explains EXACTLY why the lower portion of the brake light goes out when switching on the fog light..... if all the brake lights stayed on, that woudl mean the lamp didnt meet the criteria needed for E-Approval.
So yeah, thats where im at today. Involved in a battle between DVSA, the tester and Mercedes themselves. I think as I see it there can be three possible outcomes.
1 - The tester and his understanding of the rules is wrong and the car should pass.
2 - Mercedes and their 'working exactly as expected' diagnosis are wrong and there in fact an issue with the car
3 - Both Mercedes and the tester are right and in fact every single one of the A classes on the road with these lights which have passed an MOT in the last three years should in fact have failed.
Apologies - thats turned in to a bit of war and peace haha!! Anyways, having gone through various degrees and stages of anger and rage, i now find myself mroe intrigued to how its going to play out than anything else.
Shall keep you all posted haha!
Just thought i'd share with you some of the shambolic happenings i've encountered over the last month whilst trying to get my run of the mill A-Class through its MOT.
Car in question is a 64 plate A220 CDi. Being the AMG-Line model, its a few nice to haves on it - one of which is the upgraded lighting option with xenons up front and LED tail lights.
As i'm sure you'll agree, not exactly a rare car by any stretch of the imagination.
Bought the car as approved used from a Mercedes dealer. Part of the 'approved used' package ensures that your car will pass its first MOT in your ownership or Mercedes will cover the costs of anything needed to make that so (dare say there are a few exclusions there in terms of thigns like tyres and whatnot but, whatever, thats not relevant here).
Car's mot was due to expire mid-December, and having been in to Mercedes themselves for a major service just a couple of weeks prior, I put the car in for its MOT at my local station expecting nothing other than a pass......... however, to my surprise, i returned to collect my car a couple of hours later to be told it had failed.
Failure reason was listed as the following:
"Offside Rear Rear fog lamp adversely affected by the operation of another lamp brake light more than 50% of lights(led) extinguish when fog lamp switched on (4.5.4 (b))"
Basically, what this relates to is the way in which the rear lamp works. The sidelights and brake lights operate in a large back to front C shape pattern, made up of 27 different LED bulbs. Directly beneath this C shape lives the fog light which is positioned just under the bottom edge.
The side lights work. All 27 LED's come on exactly as you'd expect. Apply the brake and indeed all 27 LED's come on for the brake as well. Great. No problems there.
However, whilst holding your foot on the brake - if you then switch on the rear fog light - a portion of the brake light LED's go out. In fact, of the 27 brake light LED's, 15 go out and 12 are left illuminated whilst the rear fog light is on.
And for this reason, the tester has deemed this to be a fail.
So....... i get on the phone to Mercedes and get the car booked in with them to resolve the issue. They decide that they are going to order in a new rear light assembly for the car. So they get hold of the light and try the new unit only to find that the new light does exactly the same as the last one did.
They then proceed to do some digging about and come back to me after having the car for 4 days with the conclusion that the lamp is in fact designe to work that way and is working 100% correctly. Quite why it took them so long to figure this out and why it wasnt the very first thing they checked when the car went in I have no idea. Anyhow, they return my car to me complete with an extract from a technical document from Mercedes confirming that this is how the lamp should work.
Great, I think. I'll get back to the MOT station and get this resolved and car tested and passed and that'll be the end of it. Or so I thought.
Back to the MOT Station, armed with my technical information from Mercedes........ 'Nope. Cant accept that. Regardless of what Mercedes say, this doesnt meet the DVSA standard and i wont pass it till it does'.
So. Stalemate. And from this point, my only option left is to either pay someone else to MOT the car (Mercedes at this point had already confirmed they would pass the car if i took it to them), or take up the result of the test by means of a formal appeal.
In hindsight now i suspect I should have just taken the hit and let someone else MOT it - however, given that all testers are working to the same rules, if its a pass in the eyes or Mercedes, then its a pass at the station i took it to - or, vice versa, if it really IS a fail, then Mercedes cant / shouldnt pass it either.
Regardless, i decided i shouldnt be having to pay a second fee for this fi the car is in fact pass worthy - so decided to take up the appeal process....... which is where we're at now, a full month after the original test. The guy from the DVSA came out tto look at the car, took some photos and information from me and its now in their hands.
The whole thing has been absolutely mind boggling. Having spent most of ym adult life messing about with cars and being around them - this is the most shambolic experience i've ever had with regards to an MOT.
The thing which flabergasts me the most is that this isnt a 'new' car. This is this very car's third MOT from new. There are thousands of other exactly like it on the road - its certainly not rare thats for sure. How on earth has this not been flagged up before now if it is a design flaw with the lamp?!?
It gets even better when you delve in to the legislation which deals with the requirements of getting E-Approval on such lamp units which dictate that a fog light cannot be any closer than 100mm from a brake light - which to me explains EXACTLY why the lower portion of the brake light goes out when switching on the fog light..... if all the brake lights stayed on, that woudl mean the lamp didnt meet the criteria needed for E-Approval.
So yeah, thats where im at today. Involved in a battle between DVSA, the tester and Mercedes themselves. I think as I see it there can be three possible outcomes.
1 - The tester and his understanding of the rules is wrong and the car should pass.
2 - Mercedes and their 'working exactly as expected' diagnosis are wrong and there in fact an issue with the car
3 - Both Mercedes and the tester are right and in fact every single one of the A classes on the road with these lights which have passed an MOT in the last three years should in fact have failed.
Apologies - thats turned in to a bit of war and peace haha!! Anyways, having gone through various degrees and stages of anger and rage, i now find myself mroe intrigued to how its going to play out than anything else.
Shall keep you all posted haha!
Edited by ESD1711 on Wednesday 15th January 14:47
Pica-Pica said:
Why did you not get it MOT’d at Mercedes while it was serviced?
My BMW has just had its ‘approaching end of 3 year warranty’ check, so I made sure they did the MOT as well. That way there should be no issues, no failures, and no advisories.
Because, i grudge spending £58 quid on something which I can get done for about half the cost at a local garage whcih should be done to the very same standard as it would at the dealership.My BMW has just had its ‘approaching end of 3 year warranty’ check, so I made sure they did the MOT as well. That way there should be no issues, no failures, and no advisories.
In hindsight now though, for the sake of the thirty quid i've saved - it would have certainly been the better option, theres no denying that at this stage lol.
Torquey said:
I'm quite interested to see how this pans out.
Have you managed to find another AMG line A class to see if others work in the same way that yours does? I thought that's the first thing Mercedes would have done!
I'm sure scenario 1 will happen and DVSA will pass it.
Unfortunately, its of an age now where they dont tend to have them sitting at the dealers - only the newer shaped ones or indeed the later facelifted versions of mine. Have you managed to find another AMG line A class to see if others work in the same way that yours does? I thought that's the first thing Mercedes would have done!
I'm sure scenario 1 will happen and DVSA will pass it.
Whilst doing some digging I did find another case online which suggested theirs did exactly the same.
https://www.aclassclub.co.uk/threads/a45-1-or-2-re...
I haven’t read in to the full regs regarding brake light/fog lights but it sounds like, at least from the MOT testers point of view and his understanding of them that he’s doing his job right.
Having part of the brake lights go out when the fog light comes on is a little odd when you take a step back and think about it. It would look almost as if something’s wired incorrectly.
The tester couldn’t know this is how they are from the factory (Mercedes themselves didn’t, after all) and he’s following his interpretation of the rules to the letter.
I’d be interested to see the outcome of this.
Having part of the brake lights go out when the fog light comes on is a little odd when you take a step back and think about it. It would look almost as if something’s wired incorrectly.
The tester couldn’t know this is how they are from the factory (Mercedes themselves didn’t, after all) and he’s following his interpretation of the rules to the letter.
I’d be interested to see the outcome of this.
My preferred outcome would probably actually be that Mercedes themselves are in fact in the wrong and that there IS a fault with the car and the fail is legit.
Having kept the car for 4 days themselves to diagnose it, subsequently deciding its working correctly, stating to me that they would pass it themselves (in spite of the contradiction with the MOT rules) and indeed the fact I'm now coming on for a month without use of my car.......... i feel like that would put me in a pretty strong position in terms of a complaint.
Whereas if it turns out that the tester is incorrect and he got it wrong, i suspect I'll stand very little chance of anything more than a shrug of the shoudlers and an 'oh well, who knew'.
Having kept the car for 4 days themselves to diagnose it, subsequently deciding its working correctly, stating to me that they would pass it themselves (in spite of the contradiction with the MOT rules) and indeed the fact I'm now coming on for a month without use of my car.......... i feel like that would put me in a pretty strong position in terms of a complaint.
Whereas if it turns out that the tester is incorrect and he got it wrong, i suspect I'll stand very little chance of anything more than a shrug of the shoudlers and an 'oh well, who knew'.
Pegscratch said:
It's not in contravention of the rules though is it. The rules are around the fog light being affected by the operation of another light, not vice versa.
Not excusing the odd behaviour of the light, just that the MOT tester's grasp of English is flawed.
Yeah i had wondered about that also - the wordking of that is incorrect in that the fog light is not affected by the brake likght, its the other way around. Not excusing the odd behaviour of the light, just that the MOT tester's grasp of English is flawed.
However though - it does still not meet the 50% of the light needing to work rule, with 12 out of 27 leds only being on while the fog light works.
ok, I'm going to be Mr Pedantic here, the MOT handbook states:
4.5.4 (b): A rear fog lamp adversely affected by the operation of any other lamp
I would argue that the fog lamp is not affected in anyway, it is the brake light that is affected, the fog light is either on or off, and does not change with the application of the brakes.
The real failure should be:
4.3.3 (b): A stop lamp adversely affected by the operation of another lamp
Now you could argue that it is not adversely affected as it is working as designed, I await the final outcome as things like this fascinate me.
See here for details:
https://www.gov.uk/guidance/mot-inspection-manual-...
P.S. Apologies for a bit of a cross post, took me a while to gather the correct information.
4.5.4 (b): A rear fog lamp adversely affected by the operation of any other lamp
I would argue that the fog lamp is not affected in anyway, it is the brake light that is affected, the fog light is either on or off, and does not change with the application of the brakes.
The real failure should be:
4.3.3 (b): A stop lamp adversely affected by the operation of another lamp
Now you could argue that it is not adversely affected as it is working as designed, I await the final outcome as things like this fascinate me.
See here for details:
https://www.gov.uk/guidance/mot-inspection-manual-...
P.S. Apologies for a bit of a cross post, took me a while to gather the correct information.
Edited by Olivergt on Wednesday 15th January 15:07
ESD1711 said:
Yeah i had wondered about that also - the wordking of that is incorrect in that the fog light is not affected by the brake likght, its the other way around.
However though - it does still not meet the 50% of the light needing to work rule, with 12 out of 27 leds only being on while the fog light works.
It's not though is it; the lighting is only just over 25% affected. 27 per side, single sided fog light.However though - it does still not meet the 50% of the light needing to work rule, with 12 out of 27 leds only being on while the fog light works.
Olivergt said:
The real failure should be:
4.3.3 (b): A stop lamp adversely affected by the operation of another lamp
Now you could argue that it is not adversely affected as it is working as designed, I await the final outcome as things like this fascinate me.
That would be my interpretation; adversely affected is intended to weed out earth faults which cause the lights to dim. Designed that way is indeed a very different proposition.4.3.3 (b): A stop lamp adversely affected by the operation of another lamp
Now you could argue that it is not adversely affected as it is working as designed, I await the final outcome as things like this fascinate me.
I would hazard a guess that the folks that design cars and ensure it meets type approvals are markedly more intelligent than an MOT tester that can't even pick out the correct failure when trying to fail a car for "working as designed".
Pegscratch said:
It's not though is it; the lighting is only just over 25% affected. 27 per side, single sided fog light.
I did specifically query that with the guy from the DVSA, asking if the more than half applies across both sides collectively and according to him it is 50% for each side - so as it’s working at the moment it’s 12 out of 27 as opposed to 39 out of 54. I do agree with you though in that it seems hugely unlikely to me that a) Mercedes would build / design something which wouldn’t be mot compliant, and b) that even if they did, that it wouldn’t have come to light before now.
alorotom said:
Is it even that as I had always believed that the % stated was in regards to the lux output rather than volume of physical bulbs
Nah, it’s worded like this:Defect Category
(a) Stop lamp(s):
(i) with a multiple light source up to 1/2 not functioning
(ii) missing, inoperative or in the case of a multiple light source more than 1/2 not functioning
(iii) all missing or inoperative
Pegscratch said:
Olivergt said:
The real failure should be:
4.3.3 (b): A stop lamp adversely affected by the operation of another lamp
Now you could argue that it is not adversely affected as it is working as designed, I await the final outcome as things like this fascinate me.
That would be my interpretation; adversely affected is intended to weed out earth faults which cause the lights to dim. Designed that way is indeed a very different proposition.4.3.3 (b): A stop lamp adversely affected by the operation of another lamp
Now you could argue that it is not adversely affected as it is working as designed, I await the final outcome as things like this fascinate me.
I would hazard a guess that the folks that design cars and ensure it meets type approvals are markedly more intelligent than an MOT tester that can't even pick out the correct failure when trying to fail a car for "working as designed".
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