Just having one small issue with regards to the factory trailer hitch wire connector. Its a 7 pole Pollak connector and only 2 connectors seem to be correct with regards to voltage levels. The ground pin (0 volts) and the "+" terminial is 12Volts. The remaining terminals (stop, running lights, L-turn, R-turn and backup lights) all measure 1.75 Volts. It should be 12 Volts. Anyway, I tried using a test light between ground and the running light terminal and it doesn't light up. Anybody, have this issue before? I already purchased the Pollak 7 pole to 4-pole converter, but before I plug it in I need to make sure the factory plug is putting out the correct voltage levels. Thanks GaryV

 

Have you checked the voltages when it is under load? I wonder if the car has to be under load to put out full voltage.

 

Are we to assume that when you checked the right turn signal pin the turn signal was turned to right turn.............and when the left turn signal pin was checked the left turn signal was turned to left turn and when you checked the running light pin the running lights were turned on??????

 

I'll be curious on this one, too. My Audi Q7 was the same. A trailer had to be connected to test the socket. With no load nothing seemed to have the right voltages. When a trailer was connected, everything worked as it was supposed to.

 

Correct...

 

I did purchase a 7 pole to 4 pole Pollack converter and a 4 pole LED tester. I think the 4 pole LED tester doesn't put enough load to activate the factory connector. I had MB look into it and the service manager hooked up there 7 pole tester and it did pass all functions with regards to how it operates. So, this weekend I'm going to try to connect a real trailer load to see if it works....

 

Had to purchase another brand converter that was loaded with resistors. The part # is TR20141 from etrailer.com

Now my trailer connector works with my 2014 ML550

 

Are you sure it wasn't 20142? That'[s the most recent adapter from Tekonsha. I had to use one with my 2014 ML350BTC and a trailer with LED lighting - Also purchased from etrailer.com.

 

I copied and paste directly into the message box. Here it is again...
Item: TR20141


came from my email invoice...

Quite a few MB users already purchased this adapter from the reviews. I'm listed also...

 

I see the difference. The 20141 converts the 7-pi socket on the ML to a 4-pin or 5-pin on the LED trailer.

The 20142 that I used is 7-pin on the ML to 7-pin on the LED trailer.

Alles klar!