Bought a new cargo trailer. It has LED tail lights. Towed it with my '08 GL320 for the first time at night. All of the exterior lights, including the brake lights blink on/off continously, like they are blinkers. They work normal when the brake is applied but then go back to blinking afterwards.

The trailer wiring I do not think is the problem, as the lights work normal with 2 other tow vehicles (not M-B). I think the problem is the GL as I tried connecting to a different trailer and it does the same blinking lights.

Any thoughts on the problem...possibly a simple fix I can do, before I bring it in to the dealer?

 

You need a special cable that plugs inline between your trailer and the GL's plug to accomodate the LED lights. You can buy this cable online at www.etrailer.com for $25.00

http://www.etrailer.com/p-V39010.htm

Neil

 

The problem is that the LED trailer lights do not draw enough current to keep the MB trailer light controller happy. MB has a service bulletin that describes a fix - basically, 220 ohm, 1.5 W resistors can be wired in parallel w/ the LED trailer stoplights to make them work w/ the MB controller. Ask your dealer to look in the MB Workbook under "LED Trailer Lights".

 

Do you have the part # from etrailer?

 

This is rather timely.
I need to replace a light fixture on my trailer and was looking at LED's.
I was concerned about the power sensing logic in the SAM.
Guess my concern was on the money.

 

OK, here is the skinny!


The trailer shop ordered the following adapter -TowReady 20141 @ 13.99.


The part can be ordered from etrailer.com for 13.99 plus postage.


The trailer shop called to say they had the part in. I took the trailer and truck to them on Saturday morning. Conclusion. It stopped the trailer lights from blinking, but I now have a bulb out on trailer on the dash display also the lane change sensors are deactivated. The lane change sensors happen whenever you plug anything into the 7 pin outlet. After digging through the owners manual we found that, but not under trailer towing.


The adapter purchased which is a 7 to 4/5 adapter has a resistor built into the adapter. You can not see it. Although the adapter does have a bump on one of the sides of it. Do not confuse the adapter with any other adapter that has built in LED lights or no lights indicating there is a electric or bulb problem. This adapter is solely meant to stop the false bulb out and to stop the LED lights from blinking.


Just from what I have gathered this is a sporadic issue and does not present itself to all lines of Mercedes models and years.


1) My servicing Mercedes Dealer was on no help! As in totally clueless, did not care, ect... My selling Dealer suggested the trailer shop for further help. He knew of the problem but you could tell he was not wanting to sell out to the other guys!


2) The trailer shop is still baffled. They claim they sell LED trailers all to time to Mercedes, BMW, VW, Audi and Porsche owners.


3) eTrailer was very little help too! Sent back canned answers.


4) I got more help out of the Mercedes boards than these other places.


For now I'll live with the problem of the trailer bulb out. Although not real acceptable. Perhaps there is a software update out there that will fix this. Like everything else Mercedes does. I'll be dead and gone before they take action.