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2004 W163 ML500
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14 Posts
Discussion Starter #1
Hi,

On my second w163 now, must be glutton for punishment! ;)

Been working fine for the 6 months I have owned it, but now have an issue. The car is a UK vehicle 2004 registered ML500. It is equipped with automatic xenon headlights.

For some reason since a month ago every time my headlights activate (manually or automatically) the FM reception has lots of static and is barely able to be listened to. As soon as you switch the lights off the reception is perfect.

I took the back panel off the tailgate and checked the ground was clean, which it is. Removal and refitting made zero difference. I have searched the net and not really found any other examples. There was a post on here from someone in a pre lci w163 that got the same interference but only momentarily.

Nothing electrical has been disturbed before or since. Any clues?
 

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2003 ml500, 2004 ml350
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1,830 Posts
My best guess and it is only a guess. Ballast going bad? Or a ground with the light?

Brown means ground I think there is one on each side for each light
 

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W163 and General M Gremlin
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3,695 Posts
Trouble shoot by pulling off one at a time each side of the xenon connectors under the hood and retest to pin point which side.
Or possibly a relay issue - swap relays (f2k6 relay if I recall) too, to test, at the wheelwell (not sure if you have RHD or LHD)
 
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2004 W163 ML500
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Discussion Starter #4
Thanks for the replies

I found the ground for the headlights and they are easily accessible without even removing the headlight, perhaps they need checking first?

It’s a RHD vehicle, I have access to all the OEM info, so I can trace things but lack a multimeter or similar.
 

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W163 and General M Gremlin
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3,695 Posts
Thanks for the replies

I found the ground for the headlights and they are easily accessible without even removing the headlight, perhaps they need checking first?

It’s a RHD vehicle, I have access to all the OEM info, so I can trace things but lack a multimeter or similar.
You can. I'm of the thought of isolating each side to see if you can replicate the issue.
 

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2000 ML55 sold? 2013 ML500,? 2017 C43 AMG,1929 Victory 6 roadster, 1927 Dodge 4 sedan, 1929 Dodge
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5,042 Posts
As above also check the main plug to the headlights. Look into the end of the plug and check if any pins look hot or have been burnt (melted).
Mainly the tan earth lead.


Sent from my iPhone using Tapatalk
 

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2004 W163 ML500
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14 Posts
Discussion Starter #7
Thanks. I’ll check them this weekend. Probably worth checking all wart straps in the engine bay too.

Worthy of note, I have no problems with the headlights. All working
 

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2004 W163 ML500
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14 Posts
Discussion Starter #8
Finally got around to working on this.

All plugs were basically brand new condition with no melting etc. Two earths looked so so on the body behind, so I cleaned them up. Issue still present!

However, I did notice some bodgery on the N/S (uk) headlight. Looks like the plug on the igniter has previously failed. How do I know this? Well they were kind enough to tape the melted one to the outside of the igniter!! Mental. Re wiring doesn’t look the best and no heatshrink used etc. It’s got broken clips and scuffed lens so will be going in then bin.

Ordered a replacement unit on eBay and will fit when it arrives next week. Fingers crossed this solves the issue.
 

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2004 W163 ML500
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Discussion Starter #10
So today I swapped everything over to the new light.

I used the same bulbs from the old headlamp, but the igniter and ballast from the “new/used” lamp.
Swapped over the level motor which was a lot harder than it looked like it would be.

Now I have No Xenon light on that side and no sidelights?! Turn signal works but nothing else. Drivers side functions as normal and no lights on the dash.

Anybody got any ideas? I’m stumped.
 

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W163 and General M Gremlin
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3,695 Posts
Swap headlight assemblies - left to right and right to left - to determine if the headlight wiring is the problem or back further.
 

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2004 W163 ML500
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Discussion Starter #12
UPDATE: I knew it was getting power so I thought I would just swap the ballast as these things are always a problem on xenon headlights. Noticed the sidelight bulb was blown so probably missed this on installation.

All back in and working perfectly! Panic over.
HOWEVER, still have interference on the radio when lights are on :(

So swapped out dodgy wiring on the headlight, cleaned 3x earths up (only one looked bad) but the problem remains the same.

Any ideas? Could it be main earth next to battery?
 

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W163 and General M Gremlin
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UPDATE: I knew it was getting power so I thought I would just swap the ballast as these things are always a problem on xenon headlights. Noticed the sidelight bulb was blown so probably missed this on installation.

All back in and working perfectly! Panic over.
HOWEVER, still have interference on the radio when lights are on :(

So swapped out dodgy wiring on the headlight, cleaned 3x earths up (only one looked bad) but the problem remains the same.

Any ideas? Could it be main earth next to battery?
What type sound of interference?
Is the motor running too with this interference?
 

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2004 W163 ML500
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Discussion Starter #14
Static interference as soon as lights illuminate (dipped beam). Switch the lights off and perfect reception. It never used to have this issue, so I am assuming something changed or degraded.

Yep motor would be running as I don’t think xenon fire up without it
 

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W163 and General M Gremlin
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Static interference as soon as lights illuminate (dipped beam). Switch the lights off and perfect reception. It never used to have this issue, so I am assuming something changed or degraded.

Yep motor would be running as I don’t think xenon fire up without it
Manual turn on and off? No DRL, correct?

EDIT:
long shot, but read for the info.
 
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W163 W202 W203 W246 MB100D
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you may have tried this already but did you remove connections to both headlights and switch on the lights, was the issue still there? (confirming issue is within one or both of the headlight assembly or not)

good luck!
 

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2004 W163 ML500
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Discussion Starter #17
Heard about the defroster issue and also the bad earth on the bootlid. That was the first item I checked as I had not pinpointed it to the lights affecting it initially (in winter so lights almost always on)

No DRL, the lights are automatically operated (sensors) but does it if manually turned on as well.

Good shout on headlights being connected - might try this but it could also be a red herring. If there is a bad or suboptimal earth somewhere then this might be allowing the noise.

Might re check the antenna and ground in boot, see if I missed something
 

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W163 and General M Gremlin
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3,695 Posts
Heard about the defroster issue and also the bad earth on the bootlid. That was the first item I checked as I had not pinpointed it to the lights affecting it initially (in winter so lights almost always on)

No DRL, the lights are automatically operated (sensors) but does it if manually turned on as well.

Good shout on headlights being connected - might try this but it could also be a red herring. If there is a bad or suboptimal earth somewhere then this might be allowing the noise.

Might re check the antenna and ground in boot, see if I missed something
You still need to unplug each side one at a time and test, and if need be, swap headlight assemblies to test
 
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