Factory trailer wiring not working
Newbie
Joined: Nov 2022
Posts: 9
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Ml320
Have you tried one of the adapters for LeD bulbs to trick the vehicle into seeing them? If you’re in Portland, Oregon you’re welcome to try ours. Or buy one off Amazon and return it if it doesn't work.
you could also try just tapping into the rear light like an older car, but the computer might mot like that and cause issues.
you could also try just tapping into the rear light like an older car, but the computer might mot like that and cause issues.
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.
Member
Joined: Sep 2016
Posts: 104
Likes: 21
From: Portland, Oregon USA
2010 ML350 Bluetec, Alfa Romeo GTV6
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!
Good luck, I totally understand needing a vehicle up and running for work!
Newbie
Joined: Nov 2022
Posts: 9
Likes: 0
Ml320
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!
Good luck, I totally understand needing a vehicle up and running for work!
Thanks.
Super Member
Joined: Nov 2017
Posts: 558
Likes: 114
From: San Francisco Bay Area
2006 R500
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.
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.
Newbie
Joined: Nov 2022
Posts: 9
Likes: 0
Ml320
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.
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.
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.
Newbie
Joined: Nov 2022
Posts: 9
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Ml320
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?
Super Member
Joined: Nov 2017
Posts: 558
Likes: 114
From: San Francisco Bay Area
2006 R500
Something like this will be what you need: https://www.securefixdirect.com/led-...us-11291-p.asp
Newbie
Joined: Nov 2022
Posts: 9
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Ml320
Something like this will be what you need: https://www.securefixdirect.com/led-...us-11291-p.asp
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&_$ja=tsid:| cid:17631002110|agid:|tid:|crid:|nw:x|rnd:17440680 625206652630|dvc:m|adp:|mt:|loc:9046213&gclid=CjwK CAiApvebBhAvEiwAe7mHSM_p_Iyf2vL5R_UcxXpiIvNwZ8kViE fRAwwuwTM-bhIlMizOcaZ92xoCPZMQAvD_BwE
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Super Member
Joined: Nov 2017
Posts: 558
Likes: 114
From: San Francisco Bay Area
2006 R500
Yes but I'm in the UK so can't get that one... Will try find something in the UK like it but what doesn't get me is that if this adapter is what I need then why the light board like this one doesn't work as well as it uses normal standard bulbs.
https://www.halfords.com/motoring/trailers-towing/trailer-accessories/ring-trailer-lighting-board-197486.html?istCompanyId=b8708c57-7a02-4cf6-b2c0-dc36b54a327e&istFeedId=367c5610-f937-4c81-8609-f84582324cd6&istItemId=xtqlmt&istBid=t&_$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
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
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.
Newbie
Joined: Nov 2022
Posts: 9
Likes: 0
Ml320
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
