Trailer Lights Constantly Flashing

[Aboy.GT2]

I just leased a 2010 MB GL450 and when I hooked my Trailex trailer into the plug all the lights on the trailer just constantly flash. This only happens when the headlights are turned "on" in the GL when they are "off" everything works fine. I brought the GL with the trailer hooked up to the dealer and was told that since the trailer has LED lights there was not enough resistance to keep the lights on. They would have to install a resistor in the lighting system and it was not covered under the warranty. This seems strange to me since the GL comes with Daytime LED upfront and LED brake lights. I previously drove a QX56 that had LED brake lights and never had any problems with the trailer. Both cars had factory tow package. Has anybody else ever run into this problem or know if what I am being told is correct? I would think a car that has LED lights would be able to light up a trailer with LED lights. If anyone can shed some light on this (no pun intended) it would be greatly appreciated.

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[NorthVan]

I had a problem with my Touareg when the hitch kit went on, and I plugged in my trailer for the first time. The lights weren't functioning properly, turns out that it has a European trailer and NA trailer setting in electronic module that was switched via a computer setting. The default setting was for the European setting. Perhaps this is the same thing that your MB is encountering.

[Aboy.GT2]

Thanks for the reply NorthVan.

Since posting I contacted Trailex directly and they say this is a common problem with MB, Porsche and Volkswagen. They claim the cars are to smart for the trailer and continually pulse the wires to determine "something" with the connections, hence the constant flashing. I was told there is an adapter available at any trailer store called a LED converter that plugs into the connector on the car hitch and then the trailer plug goes into that. It will solve the problem and costs about $18.00. I will invest my $18.00 and keep my fingers crossed.

[NorthVan]

I think the converter prevents the LED's from throwing light failure faults on the vehicle. My trailer is new, and has the proper resistors installed to prevent this.

Let me know if your Converter solves your problem, my brother is looking at buying his wife a GL450.

[M&M]

my Porsche does that when I tow my new boat with LED. I turn on my head lights and the trailer lights stop blinking. Just got to remember to turn on the lights during the daylight.

[Aboy.GT2]

Originally Posted by NorthVan997C2S

I think the converter prevents the LED's from throwing light failure faults on the vehicle. My trailer is new, and has the proper resistors installed to prevent this.

Let me know if your Converter solves your problem, my brother is looking at buying his wife a GL450.

NorthVan,

Just a quick update. After squabbling with service mgr. and conferring with MB rep. that the most up to date GL (that comes with LED Daytime lights) should power the trailer lights. They decided to cover the modification. However once I disconnected the trailer at home and drove the car every time I step on brake or use directional I get the fault message on the dash to check trailer lights. Service Mgr. said to just ignore as this is the only way to get the trailer lights to work correctly when it is attached.

You would think MB would have this stuff sorted out already. I mean LEDs have been around for sometime now.

[NorthVan]

Originally Posted by Aboy.GT2

NorthVan,

Just a quick update. After squabbling with service mgr. and conferring with MB rep. that the most up to date GL (that comes with LED Daytime lights) should power the trailer lights. They decided to cover the modification. However once I disconnected the trailer at home and drove the car every time I step on brake or use directional I get the fault message on the dash to check trailer lights. Service Mgr. said to just ignore as this is the only way to get the trailer lights to work correctly when it is attached.

You would think MB would have this stuff sorted out already. I mean LEDs have been around for sometime now.

How old is your trailer? I have a 2008 Aluma with LED's and it is a know problem with early LED equipped trailers that the resistors are not set up properly to deal with the "intelligent" tow vehicles that read the lights on the trailer. According to the sales guy I dealt with when I bought my trailer, the newer trailers have the proper resistors built in. Perhaps you need to work with MB and figure it out with a intermediate connector that will regulate the voltage.

My works perfect, and the vehicle will tell me if the bulb is not working, but it will also set off the alarm when the car is locked (and alarmed) and the trailer is unplugged. I am sure the Cayenne does this as well.

Good Luck, but don't settle for either short coming, a $20000 NA tow vehicle won't have this problem, why should a $60000 MB.

[Aboy.GT2]

I agree, that's why I wouldn't let them off the hook so easily.

The trailer is 2008 Trailex 8045. When I spoke to the guy from Trailex he was well aware of the problem and seemed to place the blame on the car mfgs. He did not offer up any mention of updated resistors on their product though.
I will let you know if anything changes from this point but it looks like I will be staring at fault messages unless they come up with an easy fix.

As an aside, any snow yet at Whistler? I love that place and the Olympics are coming up pretty soon.

[NorthVan]

I doubt that it is the trailer, trailex makes excellent trailers. I would suggest trying some MB owners (another forum) and see what you they have encountered and what they have come up with.

[RMcG]

I had the problem with my Trailex and Porsche Cayenne. Nobodu could fix it and the ultimate solution was to replace the LEDs on the trailer with conventional lights, (which are just fine). We tried all sorts of resistors and eventually gave up.

[Aboy.GT2]

Quick update.

Here is the adapter that is supposed to cure the fault problem and enable the LED lights to function properly.

http://www.etrailer.com/pc-~V39010.h...utm_medium=ppc

[NorthVan]

Originally Posted by Aboy.GT2

Quick update.

Here is the adapter that is supposed to cure the fault problem and enable the LED lights to function properly.

http://www.etrailer.com/pc-~V39010.h...utm_medium=ppc

Let me know how it works. My brother is getting his GL 450 next week, and I want to try my trailer on his. It would be interesting to see if it is a Trailex or MB thing.

[Aboy.GT2]

Definitely a MB thing. I took your advice and searched it at Benzworld.org and there was a thread about the same problem. That is where I got the link for the adapter. It has to do with the car searching for the trailer hookup and pulsing the lines to see if there is a burnt out light on the trailer. In my case the dealer added the resistors into the wiring harness behind the right rear panel and everything works fine when the trailer is hooked up. Now I get the fault message when it is not hooked up.

I would recommend using the adapter and not mess around with the wiring. The trailer lights will work correctly and you will not have to jerk around with the dealer. Although you just will not get a message if a trailer light burns out.

[NorthVan]

Originally Posted by Aboy.GT2

Definitely a MB thing. I took your advice and searched it at Benzworld.org and there was a thread about the same problem. That is where I got the link for the adapter. It has to do with the car searching for the trailer hookup and pulsing the lines to see if there is a burnt out light on the trailer. In my case the dealer added the resistors into the wiring harness behind the right rear panel and everything works fine when the trailer is hooked up. Now I get the fault message when it is not hooked up.

I would recommend using the adapter and not mess around with the wiring. The trailer lights will work correctly and you will not have to jerk around with the dealer. Although you just will not get a message if a trailer light burns out.

Glad to hear that you have figured out the problem.

My Touareg works with out a problem, I have the factory control module, set for NA wiring harnesses in the computer. The only weird thing about the set up, is the brake controller won't work properly unless the I turn the vehicle off before plugging it in.