Flashing trailer LEDs

goatridesbikes · Dec 23, 2019

I've read through some of the threads on this. Pretty sure I know the fix.

I'm going to try one of these: https://amzn.to/35Tklho

But, here's the strange thing. 2011 Touareg.I had VW install the correct VW Towing Harness last week.

VW Part #: 7P1-055-203

Electrical Installation Kit For Trailer Hitch

Drove to pick up our Trailer, a 2019 Travel Lite Falcon 23TH with all LED lighting. Plugged it in. Everything worked great. Brake lights, turn signals, all marker lights, etc. Drove about 140 miles home with a few stops to double check that nothing was flailing around or falling off. All lights continued working properly until we made one stop about 2 miles from home.

Stopped at my daughter's house to show off the new toy. When we drove the last 2 miles all of a sudden we get the hyperflashing of the marker lights. Turn signals and brake lights continued to work fine. Just all the marker lights started freaking out.

I have two questions.

1. Why did the marker lights work fine for nearly 140 miles, then all of sudden went into LED freak out mode?

2. Should the marker lights turn on as soon as the 7 way is plugged in even though the ignition on the Touareg is still off? Seems this is not ideal as I'd have to unplug the 7 way every time we stop or risk draining the Touareg battery.

Thanks all!

redbarron55 · Dec 23, 2019

I can't answer why it worked to start with, but the trailer for my setup with a 2012 recognized the trailer to start with and then would not.
I used an adapter I had purchased for my setup with a previous TDI Sportwagen like the one you are looking at.
You can tell if the trailer is being detected by trying to open the rear hatch automatically or to close it from the switch when open.

goatridesbikes · Dec 23, 2019

Any thoughts on how the marker lights all turn on as soon as the 7 way is plugged in even though the ignition is off on the Touareg?

MycHo · Dec 24, 2019

Probably voltage leak from the ECU. To detect trailer presence, it must be sending low voltage in the circuit (usually 5 volts).

If the trailer has halogen bulbs, the resistance of the bulbs will drop that voltage to zero and the ECU will conclude that a trailer is connected. Such a low voltage is not enough for an halogen bulb to emit any light.

If you use low resistance LED instead, the voltage might be enough to light them up. And since the voltage drop is not enough, the ECU doesn’t detect the trailer.

Sent from my iPhone using Tapatalk Pro

redbarron55 · Dec 24, 2019

Quite possibly when the trailer is detected with the proper adapter the lights will behave properly.
The running lights should be a part of the tail light circuit in most US trailers.
If the side lights light do the tail lights light up as well?

tdimark69 · Dec 24, 2019

mine does this, and i noticed it mimics the security light flashing...and if i detach the trailer lights with the vehicle locked it triggers the alarm

goatridesbikes · Jan 6, 2020

Bought the LED Trailer Wiring Adapter and installed.

https://amzn.to/2ZTTEGW

Remedied almost all problems.

But when the LED wiring adapter is installed yet the trailer is NOT plugged in the Touareg thinks the trailer is connected (I realized this when the tailgate stopped opening, it unlatches but will not power open or power close).

JimJ · Jan 7, 2020

So is the adapter plugged in permanently. The system is going to detect this and assume that the trailer is plugged in.
One other way is to replace the trailer LEDs with LEDs that are compatible with a canbus

goatridesbikes · Jan 7, 2020

I mounted the adapter to the 7 Way Bracket thinking that would be best. But the Touareg thinks there is a trailer connected when there is not and will be changing other vehicle dynamics like shifting, etc I'm just going to connect the adapter when towing.

JimJ · Jan 8, 2020

I'm just going to connect the adapter when towing.

Good idea.

Flashing trailer LEDs

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