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So I got message of "adaptive main-beam assist inoperative" on the dash of my E300 W212. Usually it happen intermittently (most of the time the adaptive is working, usually it does not work when the weather is not good like heavy rain or so). However just recently I tried to replace the cornering H7 bulb with LED, when I took out the original halogen bulb I noticed I saw bare metal wires on the inside of the headlight. the insulation wire seems brittle and comes off. I immediately put back the original halogen bulb and immediately took it to the local indie. I haven't install the LED yet! I googled it it seems it happen to a lot of mercedes of the same era, they seems use environmentally friendly insulators....
However, on the way to local indie then the message pop ups. Local indie disassembled the headlights re-insulating all wires with heat shrink insulators individually. They also polished the headlight and now looks like new! However, the message of adaptive main beam assist inoperative still shows up. Did something fried?
exposed wire :o
Low beam, high beam, dancing operation when startup all working. The thing does not work is the cornering lights, auto hi beam and the low beam does not follow corners anymore (became static). I will bring the car to another shop who has xentry soon, but does anyone has any idea how to fix this issue?
The 2 components I know controlling or being as inputs for auto high beam would be ride height sensor and that camera above the in cabin mid-rear view mirror.
Hopefully a Xentry will show the possible silent type DTC (non urgent DTC).
I thought only W204 has melted wire jackets like what happened to yours.which so happened to my friend's W204 and the 5 watts T10 bulb type wires
uniquely not the hotter high wattage low or high beam ones.
The 2 components I know controlling or being as inputs for auto high beam would be ride height sensor and that camera above the in cabin mid-rear view mirror.
Hopefully a Xentry will show the possible silent type DTC (non urgent DTC).
I thought only W204 has melted wire jackets like what happened to yours.which so happened to my friend's W204 and the 5 watts T10 bulb type wires
uniquely not the hotter high wattage low or high beam ones.
Well a long time ago MB uses biodegradable wires, model like W124 , but not on W212 as far as I seen.
The heat from the halogen bulb accelerated the wire jacket polymer material aging, hence you got what you got.
You can swap the wires with silicone type jacket which is 200C+ temperature rating and its core is nickle plated copper.
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Amazon import into Indonesia is so easy, as they will calculate and charge you for everything up front, you do nothing but sit pretty at home and in 2-3 weeks it will be at ur door
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Well a long time ago MB uses biodegradable wires, model like W124 , but not on W212 as far as I seen.
The heat from the halogen bulb accelerated the wire jacket polymer material aging, hence you got what you got.
You can swap the wires with silicone type jacket which is 200C+ temperature rating and its core is nickle plated copper.
Best buy from AMAZON USA, you will get latest stock.
Amazon import into Indonesia is so easy, as they will calculate and charge you for everything up front, you do nothing but sit pretty at home and in 2-3 weeks it will be at ur door
fully import duty settled. No issue with custom whatsoever, because Amazon reputation is very clean.
btw, I just came back from local merc independent shop to do the xentry scan, and the scan result is "9003 The status of circuit 15 is implausible". According to the mechanic this is common thing happened in w212 and similar models because the insulation wires inside the headlight got brittle and causing shorts. I already explained other shop should already repaired the shorts (by installing heat shrink insulation + electrical tape) however they still suspect shorts still happening somewhere. They are confident they can fix this as they already done this many times before (and usually only needs fix on the wiring, no need to replace the module) however they cannot do it today since they are fully booked. I already booked appointment tomorrow and lets hope its not the module!
This is the Circuit or power wire tree of typical W212, for you to understand what a Circuit 15 means
.
My headlight is the code 641 Dynamic LED ,so it is different to your headlight wiring.
Your headlight is a code 621 , attached is your car data card
So the message on the Xentry as IMPLAUSIBLE ( not reasonable ) is not a short circuit DTC per se , its more of a logic thing.
This is like a report of status of power circuit 15 being not reasonable...maybe bad contact come and go or minor short come and go.
I am sure the shop can fix this issue and I hope they trace the wires to a 100% of the routing if wire insulation failure is the suspect.
This is the Circuit or power wire tree of typical W212, for you to understand what a Circuit 15 means
.
My headlight is the code 641 Dynamic LED ,so it is different to your headlight wiring.
Your headlight is a code 621 , attached is your car data card
So the message on the Xentry as IMPLAUSIBLE ( not reasonable ) is not a short circuit DTC per se , its more of a logic thing.
This is like a report of status of power circuit 15 being not reasonable...maybe bad contact come and go or minor short come and go.
I am sure the shop can fix this issue and I hope they trace the wires to a 100% of the routing if wire insulation failure is the suspect.
Just got back from local indy mercedes shop. cabling wise outside the lamp is OK, all connection and voltages normal, however the inside they cannot figure it out. They suggest to bring the car to authorized mercedes to properly diagnosed the issue. If the lighting module changed, they also cannot do the coding. They said only official mercedes dealershop can do it :O I dont think its a good idea for my wallet going to dealership.
If I purchase complete headset (used) including the module, do I need to perform the coding? Is the Crader Elite able to perform such coding? perhaps I really need to purchase those.... or learn to live without ILS
Just got back from local indy mercedes shop. cabling wise outside the lamp is OK, all connection and voltages normal, however the inside they cannot figure it out. They suggest to bring the car to authorized mercedes to properly diagnosed the issue. If the lighting module changed, they also cannot do the coding. They said only official mercedes dealershop can do it :O I dont think its a good idea for my wallet going to dealership.
If I purchase complete headset (used) including the module, do I need to perform the coding? Is the Crader Elite able to perform such coding? perhaps I really need to purchase those.... or learn to live without ILS
Honestly I do not know, but it has back up coding feature, but for which modules I don't know.
another workshop has solved the problem, replaced a broken fuse and all back to normal now. fuse no 29 in the engine bay. no need to purchase a light module/ballast
That is the most disgraceful earlier troubleshooting the 1st workshop failed to do properly and good thing you went to a 2nd workshop.... if indeed only fuse 29 was the culprit.
I can't believe ground (-) and power (+ / fuse) are not the first thing they check when doing basic electric works at the 1st workshop.
Based on my car....... and fuse 29 + 30 information
The fuse 29 and 30 get power from Circuit 15, hence that Xentry scan mentioned Circuit 15 as "implausible".
.
The next this you need to watch out will be relay J. Buy genuine MB one and don't use off the shelf Hella or Bosch relay.
Relay contact points do get worn out overtime and sooner if you have short circuit blowing the fuses.
=================
Since I now have no access to MB WIS/EPC which is back home in my Jakarta home PC and me now in Bali till mid Jan 2024......... I am curious on something : You said you only loose the light ILS feature and not the power to low beam and high beam..... are you sure both high beam and low beam were still working with the DTC being CURRENT ?
Since I do not have on hand the wiring of your headlight variant which is 6?? ( need to get its 6?? variant from MB data card ) , I can't verify if your headlight power wiring is like a 641 headlight,
where power to headlight is on purpose being cross fed by the two fuses for both headlights for their running daylight and turn signal vs low beam + high beam
So loosing 1 fuse won't kill totally one side of the headlight.
Back to your original report as per post 1 in green : So I got message of "adaptive main-beam assist inoperative" on the dash of my E300 W212. Usually it happen intermittently (most of the time the adaptive is working, usually it does not work when the weather is not good like heavy rain or so).
A blown fuse will not produce intermittent issue, it will be permanent issue.
You wrote ( in green ) : btw, I just came back from local merc independent shop to do the xentry scan, and the scan result is "9003 The status of circuit 15 is implausible".
If this DTC "9003 The status of circuit 15 is implausible" ever pops out again or that "adaptive main-beam assist inoperative", replaced the Relay J, while inspecting the fuse 29 and 30.
Only bad contact points on relay can produce intermittent fault, not a blown fuse.
That is the most disgraceful earlier troubleshooting the 1st workshop failed to do properly and good thing you went to a 2nd workshop.... if indeed only fuse 29 was the culprit.
I can't believe ground (-) and power (+ / fuse) are not the first thing they check when doing basic electric works at the 1st workshop.
Based on my car....... and fuse 29 + 30 information
The fuse 29 and 30 get power from Circuit 15, hence that Xentry scan mentioned Circuit 15 as "implausible".
.
The next this you need to watch out will be relay J. Buy genuine MB one and don't use off the shelf Hella or Bosch relay.
Relay contact points do get worn out overtime and sooner if you have short circuit blowing the fuses.
=================
Since I now have no access to MB WIS/EPC which is back home in my Jakarta home PC and me now in Bali till mid Jan 2024......... I am curious on something : You said you only loose the light ILS feature and not the power to low beam and high beam..... are you sure both high beam and low beam were still working with the DTC being CURRENT ?
Since I do not have on hand the wiring of your headlight variant which is 6?? ( need to get its 6?? variant from MB data card ) , I can't verify if your headlight power wiring is like a 641 headlight,
where power to headlight is on purpose being cross fed by the two fuses for both headlights for their running daylight and turn signal vs low beam + high beam
So loosing 1 fuse won't kill totally one side of the headlight.
Back to your original report as per post 1 in green : So I got message of "adaptive main-beam assist inoperative" on the dash of my E300 W212. Usually it happen intermittently (most of the time the adaptive is working, usually it does not work when the weather is not good like heavy rain or so).
A blown fuse will not produce intermittent issue, it will be permanent issue.
You wrote ( in green ) : btw, I just came back from local merc independent shop to do the xentry scan, and the scan result is "9003 The status of circuit 15 is implausible".
If this DTC "9003 The status of circuit 15 is implausible" ever pops out again or that "adaptive main-beam assist inoperative", replaced the Relay J, while inspecting the fuse 29 and 30.
Only bad contact points on relay can produce intermittent fault, not a blown fuse.
yeah I was surprised also, because if the first shop follow xentry troubleshooting procedure first thing they should check is the fuse. apparently they skipped that. They permanently lost a customer for sure. This second workshop also fixed other complaints I had (rattling noise, not working front parking sensors), all done in 3 hours lol.
> are you sure both high beam and low beam were still working with the DTC being CURRENT ?
Yes I'm very sure both high beam and low beam were working. The only thing that does not work is the cornering light and the direction of light following the steering angle. I'm also not sure if the fuse blown why the others still working lol. Btw, I ordered the scanner you recommend cannot wait to get it. Thanks again for your help! greatly appreciate it. Happy holiday!
12-18-2023, 09:33 AM
which so happened to my friend's W204 and the 5 watts T10 bulb type wires
cannot wait to get it. Thanks again for your help! greatly appreciate it. Happy holiday! 
