LED rear tail light turn signal failure.
Recently, I was getting an intermittent rear left turn signal error on my 2009 ML320. When I was on vacation it went out permanently (although it did work for a short period of time after a rain storm).
I've spoken with Mercedes and they've changed the part number of the tail light assembly and there's a new gasket seal. Apparently this is a known problem with water getting in and messing up the led pcb boards.
So, I've had the tail light assembly out in an attempt to try and clean any corrosion on the boards that could be causing the failure. Only 2 boards are partially visible. Short of just pouring RA in the assembly and letting it dry out, does anyone know if it's possible to get at the boards inside the assembly?
Thanks,
Chad
I have recently had same/similiar problem with right side tail light in the signal portion of the assembly- the 2 adjacent leds on left side of the upper row of 4 leds do not work at all. Remaining 2 leds on upper row plus the lower row of 4 leds "work" albeit very faintly. Other than that the rest of the assembly works!
I have assembly dismantled- it is not sealed- it does not require cutting with a dremel. Heat with a blow dryer the edge of assembly-gently pull off lens while heating at same time. Start pulling lens apart at "tapered" end first. Lens "sealed" on to assembly with silicon but mine came apart easily- silicon dry/old and hence possible reason for issues. At back of assembly- a total of 5 small screws need to be removed to access pcbs - 2 at top, 2 at bottom, and there is 1 hiding under the foam where bolt is at "tapered" end. This gives access to the pcbs- a total of 4 pcbs. The pcbs are held on by a total of 10 smaller screws. LED lights are surface mounted to the pcbs.
This is where I am stalled. Help if it is out there!?
I did solder a 10amp copper wire ground to metal part of light assembly as poor grounding is frequently noted in forums as a problem. This did not fix my signal problem. The leds are surface mounted and appear to be of a plastic weld/solder and I have not been able to locate the same type of leds on line.
I have not given up- but definitely at a full stop. It is possible to trouble shoot the pcbs but I need to read up on that.
Trying to avoid having to purchase a brand new assembly for appox $300-$500.
Thomas
Dealer says a leak on the driver's side caused its malfunction, indicated by rust on a bolt near the light assembly. I've read about very similar issues on other forums so we're certainly not the only ones.




Passenger side LED rear Turn flickers and barely lights up.
Do I need a new tail light?




I haven't pulled the old one off yet. I'll post comparison pics soon. But the new one doesn't seem to show any different gaskets or seals.
Something tells me I got one of the original designs.
Trending Topics
I haven't pulled the old one off yet. I'll post comparison pics soon. But the new one doesn't seem to show any different gaskets or seals.
Something tells me I got one of the original designs.
The Best of Mercedes & AMG








Now I had an issue this week on my other taillight. Old part number. The turn signal was flickering when the lights were on.
I pulled it out. Turned it upside down and a cup of water came out.
I then put it in the oven for 20 minutes at 175f and then blow dried it for another 20 mins.
Then I put clear silicone around the outer edge to create a better seal.
Good as new and works as intended. Saved myself $600.




I betcha if I plug it in it will work fine.
If that's the case I'll seal that one to and give it to my boss who has an ML with a burnt LED.
And I'll expect a raise.




Part #164 826 00 07 x two.
Last edited by Maj. Dundee; Apr 12, 2017 at 05:22 PM.
When the lamps stop working, do you get a message on the Inst. Cluster that the aux. lights are servicing the stop lamps?
Remove spare tire and everything else including the mat. If you don't have any obvious water, close the tailgate and use a high pressure water hose around the right rear tail light and you might find that water is entering the interior.


