I bought the wiring adapter fro eTrailer. I'm actually on my second one! First one I think was a knock off. The packaging and contents were a bit questionable. When I complained to eTrailer they sent me out another one. Different packaging and seems to work.

When you plug it it, the system knows this and deactivates a few features, the adjustable suspension, the blind spot mirrors. You have to idiot proof the world from being stupid!

When I first had the problem and the lights went bananas. Mercedes was of no help. They pleaded stupid. The dealership I use is a Penskie shop. They own the two that are closest to me. There are others but that only means I have to drive further!! To coin a phrase nit-whits comes to mind.

I have the GL550 so there should be plenty of ponies under the hood to pull the skis. I can attest to this: the entire thing sucks, period! The truck handles like crap. I have since bought a Toyota truck to pull the skis and do the dirty work. I still have the Lexus LX570 which did a fantastic job at pulling the skis. The only reason I went with the truck was I could put stuff in the bed and not tear up the inside of the Benz and Lexus.

When the Benz checks out that will be the last of Benz ownership.

 

 

my quest started when the manufacturer of the trailer switched out the lights to LED lights. The trailer worked fine prior and on the other tow vehicles. When the trailer was hooked up the light blinked. I approached Mercedes who were of no help. I contacted etrailer who advised on the adaptor. They sent me one that did not work and then sent another one that did work.

There is also a way way you can add a resistor between the trailer and tow vehicle. So you don’t hinder another tow vehicle if that switches! In other words if I switch to my Lexus from the Mercedes I would be screwed. You can put the resistors on the trailer itself but that would hinder if I towed with another trailer.

The adapter that etrailer sent sent was questionable. The packaging had numerous grammatical errors. Also someone could have switched out the adapter for a plain adapter. The second one like I said does work. But I do loose some automation in the process.

 

Thanks for the reply. I may try to order another adapter from ETrailer since they seem to have some of the units fail. However, if additional resistance in the circuitry is the solution to a problem that has been identified for years on MB and other European vehicles, why doesn't MB just integrate a small resistor into the trailer wiring circuit? Very frustrated with the MB lack of a professional solution

 

 

OK here's an update on the problem...I also posted this in the Sprinter-Source forum....

Well, today I picked up my 2017 Sprinter based Winnebago from the local service department. They have had it and my boat trailer over 3 weeks in an attempt to figure out and solve the flashing trailer light problem. It took them all that time to give me a straight (?) answer to the cause and potential MB solution. They explained that they finally found out that the hyper flashing issue is the result of a design feature of the Sprinter chassis. The system is designed to send a very low voltage pulse through the trailer wiring to sense if there are any trailer lights that are burned out. I presume there would be a warning light on the dash so stating. This very low voltage pulse is apparently being sent even though the lights and ignition are off. The technician explained that they could do a work around by rewiring the light module to send the pulse only when the key was turned on. Sounds reasonable, right? The only sticking point is that the workaround is not a warranty type issue and I would have to foot the bill for the fix.....wait a minute....the company recognizes the problem with all new trailers equipped with LED lights, but the fix to cause the pulse to cease when the ignition is off is the responsibility of the customer?? They think the cost is only $200 bucks or so, but it is irritating that they expect me to foot the bill for a fix that has surfaced many times over many years to many clients.....tan't fair McGee!!

 

They told me if I cut into my wiring harness and did any DYI engineering that would negate my warranty.

Yes, he's correct with the voltage sensor theory.

The LED lights flash because they draw very little voltage compared to the old style incandescent bulbs. My issue reared it self when the trailer manufacture replaced the trailer lights as I kept burning out the lights constantly. I would have a small supply of bulbs when I used the trailer. After many trips back and forth from PA to VA, the trailer folks located in PA relented and paid for LED lights to be installed by the local trailer shop in VA. They deduced the issue to vibration on the bulbs causing the burning out. When I picked up the trailer everything work great as I used the Lexus to pick it up. The LED lights worked great on all my vehicles until I hooked it up to the Benz and then the notorious blinking started. The trailer shop said they saw this before on Volvo's. I'm guessing not many Mercedes owners tow?

The adapter that eTrailer sells has a resonator built into it. I don't have the packaging anymore, but as mentioned prior it had grammatical spelling errors all over it. The first thing that came to my mind was knock off. Also as said prior the first one did not work period and when I complained, they sent another one to me and it works but it does kill off some the Benz features. The BSM for sure, the adjustable suspension and some other stuff. I've not used the Benz to tow for a while. I have the Lexus and just bought a truck last fall. I got tired of trashing the inside of the Benz and the Lexus to do my dirty work. The Benz did a crappy job of towing anyway.

I had a VW Tourag that we lemoned that we used to tow with. I do remember when you plugged the trailer in to that vehicle I never had any electrical issues like the Benz, but like the Benz it too killed off many features. The BSM, Parking sensors, Rear Camera and when you backed up it displayed a trailer on the infotainment screen warning you that you had a trailer attached.

On my Lexus everything works and nothing gets dumbed down. Back up camera, BSM and parking sensors all work. It works great as I can move the camera down when hooking up and see where the trailer is or leave it and see the entire deal.

I would stick with he adapter for now. If you modify the trailer and hook it up to something else, you may cause issues. I know it's a PITA and you paid a butt load of greenback for the motorhome.

 

Everyone - just hold on a minute. Yes, mine does it too with the Trailex for the race car - but how is this a problem? The very low-voltage pulse that the car sends is indeed to check for burnt out lights on the trailer. If you have a resistor or one of the adapters, you're only disabling a safety feature. What gives?

 

[QUOTE=Diabolis;7416864]Everyone - just hold on a minute. Yes, mine does it too with the Trailex for the race car - but how is this a problem? The very low-voltage pulse that the car sends is indeed to check for burnt out lights on the trailer. If you have a resistor or one of the adapters, you're only disabling a safety feature. What gives?[/QUOTE

All the lights on the trailer blink! Where TF have you been? OTL?

The adapter or the resistor kills the blinking lights on the trailer. I don't know about the rules on the road up north but here in the Grand Ole USA we can't have blinking trailer lights going down the road!

The OP is stating that Mercedes and or Sprinter one in the same were clueless as to what the problem is. I found this to be the case too. More like complete idiots!

Without the trailer the warning on the dash of bulbs being burned out is OK! It's just when the trailer is hooked up to the tow vehicle the trailer lights blink/flash/rapid on off. Can't have that!

So the work around is either buy the adapter or install resistors on the trailer. The problem is if you install the resistors on the trailer and tow with another tow vehicle you may have problems? On my end I have several tow vehicles other than the Benz and I'm not about to test that theory out by melting down my electrics because I got stupid and or lazy one day. The trailer shop that did the lights on my trailer would not take any responsibility if that happened. So I have the adapter and I have placed a tag on it to only be used on the Benz.

At no time was anyone trying to beat the safety system!! Just trying to get the trailer lights to stop blinking/flashing/rapid on off when hooked up!!

 

Wait a sec... you mean the lights are blinking while you're DRIVING? I see the very low blinking when the car is parked at night with the trailer connected... but they certainly operate normally on mine while driving.

 

Yes, all the lights on the trailer, blink, hyper flash, turn off and on rapidly, what ever you want to call it. It's like having your emergency lights on, but in hyper mode.

There is no faintly, barely noticeable, once in a while, only this or that hyper flash, turn off and on rapidly, what ever you want to call it. it's full on hyper flash, turn off and on rapidly, what ever you want to call it. I'm sure its 100% ticket-able here in the US if used on a public roadway.

I'm driving a 2012 GL550 with the factory hitch! This only happens when using the Benz. My other tow vehicles do not experience this what so ever. I use the normal 4 to 7 pin adapter when using those tow vehicles. As mentioned in the previous post I have a tag on the Benz adapter to use only the Benz adapter on the Benz. On the other one it says not to be used on the Benz!! On the trailer tongue I have a plate that states this too. I'm the only one in the family that hooks this all up when it's tow time. The rest of my family is OTL and would not know how to get out of a wet paper bag. I've tried to idiot proof it, but like all idiots in the world someone will figure it out and I'll be hosed!

 

Ahhh.. that's a different story altogether. I thought that they worked perfectly while you're operating the vehicle, and you see the faint periodic flashes only with the car turned off (which is what happens with mine and also what the OP was describing in the original post from 2014).

What you're describing is a compatibility issue with the trailer as it is internally wired for a 4-pin connector, which combines the brake lights and the turn lights on the same lines. The Merc is not designed to work with a 4-pin trailer. It sees the wrong resistance.

 

 

Tell them you have an alarm system that monitors the trailer as well.

I too was at first concerned about the current draw and whether said blinking would drain the battery, but the draw is so small that it is negligible (about a milliamp during the flash itself). In comparison, the car uses 100 times as much power just "listening" for the digital code from your key fob or waiting for you to touch the door handle.