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2004 ML270
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531 Posts
Discussion Starter #1
With the headlight stalk in the auto or dip main beam position the high beam lights will randomly come on.

The dash indicator light comes on as well. I can usually make it go back to dip by flicking the stalk forward then back again but it will randomly flick back to high beam.

Has anyone come across a wiring diagram for these? I understand that the headlights are controlled by the AAM. Is it possible that a faulty light stalk could cause this?

Thanks in advance.

Matt.
 

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2003 ml500, 2004 ml350
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943 Posts
Sounds to me like the stalk is at issue. If it randomly switches but goes to the desired setting when you move it, seems to me that is the problem. Does the stalk feel a bit floppy and loose?

edit:

Re reading your post, you are saying the stalk does not move on its own but going say position 1-2back to 1 sets it back to low beam.
 

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2004 ML270
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531 Posts
Discussion Starter #3
My 2004 ML270 with standard halogen headlights has an issue whereby it periodically activates high beam when the lights are on low beam. The dash indicator light comes on and the lights switch over to high beam. This happens randomly and only when the low beam lights are on. Selecting high beam normally works fine.

Trying to track down a wiring diagram so I can do some troubleshooting. I assume that it's a faulty combination switch but want to ensure there are no other modules in the circuit like the AAM.

Have found pre 2002 diagrams that show the Xenons but nothing that matches my spec. Thanks in advance.

Cheers
Matt.
 

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w163 02 ML500 W210 97 E50Amg w202 99 C230K w124 - need more space, time to build again
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2,201 Posts
mattman,

read here:

you asked the SAME question less than a month ago.
Don't start a new thread on the same topic.




Mods, please merge the two.
 

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2004 ML270
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531 Posts
Discussion Starter #5
Thanks for your reply, sorry for the additional post. Have searched all the forums and read the post you have linked which doesn't really contain any useful info. I reposted as I am specifically looking for a wiring diagram this time.

Cheers
Matt.
 

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2004 ML270
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531 Posts
Discussion Starter #6
For those interested I have found the Mercedes factory diagrams. It's a bit complicated to get it working due to the age of the software but with a little patience it can be done.

Here is a torrent link to the Star Finder software :- Mercedes Benz StarFinder v3 2008 :: RuTracker.org
Torrent is safe and clean, I used UTorrent to download it.

Mercedes have released an update to allow this to work on newer computers

And the link to the Autodesk software to get this working

I had to enable blocked content and compatibility mode to get it all working in IE but that was straight forward. My setup is a standard Win10 Pro 64bit system.

Hope this helps someone.

Cheers
Matt
 

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2003 C320 coupe, 2000 ML320
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673 Posts
Mate, .. even with the schematic, it's going to be hard to pin it down with an intermittent failure.. If you can't determine what it is once you get into it.. Try to duplicate the conditions in which it fails.. Example: (1) It does it on cold rainy nights.. On a cold day, hose the car down... (2) hot humid nights.. Put a blanket over car with a coffee pot making steam to inject under blanket.. (3) does it going down hill, jack the car's rear end up,..etc Also,.. check with family "Did anyone spill their coffee on the column? .. Did anyone run the car through a deep puddle?.. Anyone seen any signs of mice?..


I know one thing for sure.. You've got some pissed off people, in the on coming traffic when those brights decide to come on..
 

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2004 ML270
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531 Posts
Discussion Starter #8
Thanks for the reply Bobby.

It's reasonably repeatable now, it's got more frequent. To avoid blinding people I have removed the high beam bulbs for now. Low beam is good enough.

I have found the schematic and had a look and there is a white wire on pin 5 of the connector to the combination switch that is the high beam or flash wire. This runs to the AAM and then out again as a white wire to the K6 relay which then has a white wire to the high beam bulb.

Should be able to check and see if the pin 5 has B+ when the high beams turn themselves on, if so then it will be combination switch that is faulty. If there is no B+ there then it means the AAM or K6 relay is faulty. If there is B+ at the pin on the K6 relay with it removed then the AAM is faulty, if not then it will be the relay.

I am hoping that in order of failure preferred, its relay, combination switch, AAM. I don't have a 70mm T30 torx bit so can't remove the airbag yet as I will start testing at the switch.

Cheers
Matt
 
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