njlarry

I look forward to using my 2010 ML 350 for towing and have purchased a 7 to 4 pin connector. When I test it with a led test plug the lights on the tester just flash in what appears to be an alternating sequence. So it does not look like I should expect the trailer lights to work properly.
What could be wrong??
Thank you for any insight.

marc hanna

Do you have the factory wiring harness installed or an aftermarket?

njlarry

I have the factory-installed towing package.

marc hanna

I wonder if it's not drawing enough current. Try rigging up some incandescent bulbs to see if works properly then.

drolnz

I have been advised 2 different solutions....one is that the ML does not work with LED without the proper adapter.........the other is that you need to have the headlights switched on for the plugged lights to work.
My '11 Ml 350 works fine with incandescent trailer lights.

marc hanna

It's probably the LEDs tripping you up.

njlarry

Thank you both. I will try your suggestions and report the back on the result.

Penn

Mercedes sell a resistor pack which allows you to run LED's without any problems.

owengrad

I purchased this for my 2010 ML350 BlueTec, and the LED trailer lights work great!
http://www.etrailer.com/Wiring/Tow-Ready/TR20141.html

Jim

owengrad

I purchased this adapter for my 2010 ML350 Bluetec, and my LED trailer lights work great.
http://www.etrailer.com/Wiring/Tow-Ready/TR20141.html

Jim