# Trailer Lights Plug Pulsing



## Tank4all (Mar 29, 2019)

*Trailer Lights Plug Pulsing (SOLVED)*

Bought a new Atlas with a dealer installed trailer hitch. The vehicle however did not come with a trailer light socket (just the flat plastic cover). I checked the forums and purchased the Pollak from Amazon instead of the dealership. Install the 7 pin and used a multi-meter to test the power but all I'm getting is a pulsing 3 volts on most of the terminals. I checked the Pollak and the connectivity was all correct. I tested the plug coming from the vehicle and still only have pulsing power. None of the terminals was 12 volts. I tried the flashers with the engine on and off with all the same results. I'm reading that VW's enter a "trailer mode" when a trailer is attached and the blind spot, rear parking senors, eco mode all turn off automatically. Does trailer lights plug only work when the vehicle enters "Trailer Mode?" I do see multiple fuses labelled "Towing recognition control Module" in the driver foot well. 

I called the dealership I got the car from and they said they will look at the plug but it'll cost $138 to diagnosis but if it is a warranty problem it's free of charge. I found this really annoying. 

My question is - have others seen the pulsing on the trailer light plug on VW SUV's when a trailer is not attached? Is the trailer mode true? I'm about to go to a local Uhaul and just rent a trailer to tow around the block to test the plug before I go to the dealership.


UPDATE:
Thanks for the responds to my post. I went to a local Home Depot tool rental location and asked if I could just plug in a trailer to test my lights. Once I had a trailer plugged in all the lights worked. Didn't even setup the hitch ball or move the car. Once I unplugged the trailer I did get warning lights on the dash to check the lights on the trailer. I guess chalk this one up to "German engineering" and making the trailer light plug super complicated.


----------



## GTINC (Jan 28, 2005)

So, you have a non-VW hitch and a non-VW harness and you are asking why it does not function correctly? Is that the case?


----------



## vwbugstuff (Mar 27, 2004)

You are correct - the module needs to sense a load in order to work correctly.


----------



## Chris4789 (Nov 29, 2017)

I also use the Pollack 11-892P connector from Amazon and it works fine. I'm sure the VW trailer plug is different from the “standard” simple trailer connector many of us are used to on a vehicle which can provide easy testing with a VOM, as you are mentioning. 

Some searches in the on-line manual show a lot is happening at the plug: 
-Inserting the trailer plug activates the “Trailer support display” showing “The semi-circular green and red lines indicate the distance from the towing hitch…” “The orange line indicates the predicted path of the towing hitch” and other functions through the dash monitor. 
-The dash monitors the trailer turn signals to tell you if there is a malfunction as the <--1--> indicator light goes out when a turn signal on the trailer or the entire trailer lighting system is not working.
-If a factory-installed trailer hitch is connected to the vehicle electrically, then only the button on the trunk lid is active. The switch in the driver door and the button on the remote control vehicle key are deactivated.
-In vehicles with Driving Mode Selection, the start-stop system is automatically switched on in the Eco driving mode.
-etc., etc. 

[also from the manual] Do not exceed the power ratings listed below
Electrical load: Maximum power
Brake lights total: 108watts
Turn signals per side: 54watts
Side marker lights total: 100watts
Taillights total: 54watts

I’d say to ask a friend or neighbor who may have a trailer to allow you to do a test connection. Or to go to U-Haul and they should allow you to test it as they also want to be sure the lights work before you rent.
Good Luck.


----------

