I'm from UK so sadly too far and I didnt try the adapter however I tried 3 different trailers and 2 of them are standard bulbs which get no power at all and the new trailer which has LEDs, I can only seem to get the indicators sweeping at all times the second I connect the 7 pin socket (no other lights working. Checking with multimeter I have voltage for indicators and a positive but no other voltages.

I really am considering to directly wire a new socket to the tail light wiring as I need the trailer running as I am using for vehicle recoveries which is my main job and I'm losing money every day wasting time on this

https://www.ebay.co.uk/itm/312781228...mis&media=COPY
was thinking to install this to the tail light and a new socket running up to this, would it work without causing issues with the car?

Thanks.

 

I'm not sure if that will will work, but it looks way more advanced than the versions I was thinking about. You might try searching on eTrailer.com, it's US based, but they have a good question / answer section.

Good luck, I totally understand needing a vehicle up and running for work!

 

Reading the description for it, it does look promising as it says it bypasses the whole canbus system and gives a direct 12v from the battery. Also that the relay draws very little resistance so it doesn't upset the bulbs and wiring etc, I can't really see why it shouldn't work? Will try etrailers as well but really need to do something about this

Thanks.

 

Given that you are getting something with the LED trailer lights, my thought is that you have just enough bad wiring/poor connections that the Mercedes doesn't recognize that there is a trailer connected with the trailers that have regular lights. Get an LED adapter and test it with the LED trailer.

When the Mercedes detects a trailer with LED brake lights without the adapter or both brake lights dead (it sees them the same), it will supply all lights (brakes and running lights) at half power and won't activate any brake or turn light function.

 

I will admit the wiring is not the best on old trailer as it got pulled and then I had to rewire it back together by just joining the wires and heat shrinking them so maybe that trailer doesn't get detected at all for that reason however saying that I tried a light board with trailer socket and that also didn't light up but the wiring on it was not damaged.

You could be right in saying I might just need an adapter and even though I have ordered the eBay bypass relay and socket I didn't fancy cutting into the factory wiring so I would like to give the adapter a go first before I do decide to splice into the tail light wiring so what adapter would you recommend? I am in the UK if that helps. Thank you.

 

I also can't seem to find the LED adapter in the configuration I need. My led lights are all hooked onto the generic 7 pin trailer plug and the car has a 7 pin plug as well so the adapter I need is a 7 pin to 7 pin. Looking online all I can find is 4 pin to 7 flat and 7 flat to 4 etc but no 7 pin to 7 pin... can someone guide me?

 

Something like this will be what you need: https://www.securefixdirect.com/led-...us-11291-p.asp

 

Yes but I'm in the UK so can't get that one... Will try find something in the UK like it but what doesn't get me is that if this adapter is what I need then why the light board like this one doesn't work as well as it uses normal standard bulbs.

https://www.halfords.com/motoring/trailers-towing/trailer-accessories/ring-trailer-lighting-board-197486.html?istCompanyId=b8708c57-7a02-4cf6-b2c0-dc36b54a327e&istFeedId=367c5610-f937-4c81-8609-f84582324cd6&istItemId=xtqlmt&istBid=t&_$ja=tsid:| cid:17631002110|agid:|tid:|crid:|nw:x|rnd:17440680 625206652630|dvc:m|adp:|mt:|loc:9046213&gclid=CjwK CAiApvebBhAvEiwAe7mHSM_p_Iyf2vL5R_UcxXpiIvNwZ8kViE fRAwwuwTM-bhIlMizOcaZ92xoCPZMQAvD_BwE

 

The link I posted is a British store, did you even bother to look? Also, I'm in the US so it's hard to search for UK specific stores. Take the part/model number from that site and search for a store that will sell it. Or search based on the description, I was looking for 7-pin canbus trailer adapter.

As for why it doesn't work with your lightboard... Have you verified it on another car? It could be that the halogens don't draw enough power or something is broken somewhere.

 

Sorry mate don't know how I skipped that, I did try Google the same adapter and others but can't find it anywhere to buy so I guess I will have to wire everything up to the tail lights as I have given up chasing this issue