Inner tailgate light partially not working

[Abb]

I have noticed that a section of the the inner tailgate light on the ML (2012 W166) has stopped working intermittently. I removed the unit stupidly thinking there would be a bulb of some description which required replacing, only to be face with a PCB.
It all looked in tact and I couldn't see anything obviously wrong. Enquired with MB again, stupidly thinking I could buy a replacement PCB, only to be told I needed the complete light fitting at a cost of approx £200!

All seems a bit bonkers to me having to buy a complete unit when the PCB is obviously removable/replaceable.

Any suggestions on how can I can fix my current light or do I have to give in and go to the stealer?

Some pics to help explain my plight!

 

[Abb]

 

[Petrol Pete]

Nice shag pile..you are not Austin Powers are you ? I would be tempted to try and find an electronics repair place (maybe the type that do car instrument clusters etc.) and ask them to test it. Its likely to be a component failure as the whole thing did not go up in smoke. worth a try.

 

[Petrol Pete]

I did notice that the 3 soldered points on TP22 are in line but on the reverse side the white connector block that is soldered to TP22 is on the 'wonk' (technical term) has it ben twisted and one of the contacts is broken ?

 

[clk320x]

The car is scrap Abb, I will buy it off you for £1000 to help you out? Let me know!

 

[Abb]

Nice shag pile..you are not Austin Powers are you ? I would be tempted to try and find an electronics repair place (maybe the type that do car instrument clusters etc.) and ask them to test it. Its likely to be a component failure as the whole thing did not go up in smoke. worth a try.

It is not a shag pile BUT I am AP

I did notice that the 3 soldered points on TP22 are in line but on the reverse side the white connector block that is soldered to TP22 is on the 'wonk' (technical term) has it ben twisted and one of the contacts is broken ?

Cant believe I missed that, I will take your advice and get it to an instrument cluster repair type of place. Many thanks for the idea!

The car is scrap Abb, I will buy it off you for £1000 to help you out? Let me know!

I will send you my bank details Abs, but only once I have fixed the fault, it's the least I can do for your kind offer!

 

[Deleted member 131833]

Do you have a soldering iron?

Use copper braid like the braid in a screened cable and heat up the joints and place the braid onto the molten solder which will act like a wick. Then the connector will lift off

I would just hard wire the wires directly onto the board be careful though too much heat and you could lift the pads on the PCB.

If you are not sure about soldering any tv repair shop would do this for you, just don’t tell them it is off a Merc, it will cost more

Oh and I bid 1001 for the car!

 

[Petrol Pete]

Do you have a soldering iron?

Use copper braid like the braid in a screened cable and heat up the joints and place the braid onto the molten solder which will act like a wick. Then the connector will lift off

I would just hard wire the wires directly onto the board be careful though too much heat and you could lift the pads on the PCB.

If you are not sure about soldering any tv repair shop would do this for you, just don’t tell them it is off a Merc, it will cost more

Oh and I bid 1001 for the car!

What's a TV repair shop Granddad ?

 

[Deleted member 131833]

Impertinent puddle jumper, it is the place you go to to get the battery charged for the radio set

 

[Codger49]

Just wondered if the leftmost pin of TP22 is displaying the 'ring' of a dry joint?

 

[Petrol Pete]

Impertinent puddle jumper, it is the place you go to to get the battery charged for the radio set

Or the valves

 

[Abb]

Have spoken to my brother who's going to make some enquiries on my behalf (I am currently away with work commitments) before removing the light cluster again, with a very reputable local auto electronics place to see whether they can test the functionality of it and carry out a repair.
Will keep the thread updated with any developments.

 

[b1g1an]

Just wondered if the leftmost pin of TP22 is displaying the 'ring' of a dry joint?

Yep, for intermittent electrical faults, dry joints are the first port of call. The angle of that connector doesn't look to clever though.

 

[Abb]

Finally got round to doing some fault finding having replaced the light, so thought I would conclude the thread.

In a nutshell, there was nothing wrong with any of the PCBs pictured above and they all functioned correctly. Having read similar issues on the E212 (IIRC) the remedy there was to cut an access hole and re solder some connections, which got me thinking, perhaps there was some other PCBs within the unit, so I set about armed with a dremel and lo and behold....



As can be seen in the last pic, the PCB has suffered from water ingress to the fitting, which is bizarre as the light unit is completely intact. The missing LED (white square) fell off in the dissection process.

So for anyone else suffering from either 1 or more led strips not illuminating on the inner tailgate of a W166 ML, this is more than likely the culprit.

 

[Abb]

Incidentally, when I did order a new unit I was told the part number had been superseded so the new part number was used. When the light arrived, it appeared to be the same BUT the socket of the light which the wiring harness of the car plugged into was a different colour (white) and not compatible with the vehicle plug.

The light was subsequently returned and the correct one provided.

The light is fitted and all working correctly.

The end.

 

[ThorpyJ]

I seem to have the same issue as you. Just back from the garage, I thought it would be a bulb replacement, but the whole assembly needs replaced, which is £230 inc labour.

The garage said the part is actually on back order with mercedes, call back in a couple of weeks. They also said, keep an eye out for a recall from Mercedes on this part?

In any case, thought I may look online for the part, can anyone advise the part/part code to search, or find me a cheap on the in UK

 

[Abb]

The revised part now comes with a wiring loom to make it compatible, it is approx £175 from MB. All the info you need regarding part numbers is in the 1st post You are welcome.

 

[ThorpyJ]

Thanks Abb,

I checked the part number in your first post and I couldn't find much. Will this listing on Ebay fit? 2012-2014 Mercedes Benz A1669068501 | ML Class Right Side Trunk Light (New!) | eBay

 

[Abb]

That look like it would fit BUT why it has a different part number to what was on mine, I don't know. It does look as if it is considerable darker too, again that nay be the quality of the photograph and lighting conditions.

The cause of these failures is water ingress, despite them looking like a very well sealed unit. Mine was completely undamaged but did have quite a fair bit of water inside.

There has been some suggestion/indication the water is ingress is due to the rubber seals breaking down with age.

The revised part (to prevent water ingress apparently) has a white connector for the vehicles wiring loom to plug into, the one you have linked to is the old black version, so you may end up with the same issue down the line.

If you have a few tools (T15, T20 torx drivers, trim pry tools, 8, 10 mm socket IIRC) you can tackle this job yourself BTW.

Just for your future ref when comparing/looking for parts, they normally start with an A followed by 10 digits altogether or spaced apart in groups of 2 or 3.

As per pic (same as 1st post) the 166 at the beginning denotes the chassis designation of your vehicle. Ignore the fact the arrow is pointing to the 0, I was just trying to illustrate the location of the part number of this particular part.

Hope that makes some kinda sense!

 

[SuffolkSifter]

Has anyone tried to claim this a a recall or failure? I have spoken to MB and they didn't say no and then asked which branch I would like to book in to. I have yet to get conformation from my local MB, but it's worth a try even if they won't do it FOC, maybe will put something towards it? After all the recognise it as a failure in manufacture and have made an improved unit to fix the issue.