A new twist to trailer light issues. help needed

**harks11** · 15-06-2014, 06:43 PM

I have a 2008 TDI which is still going like a dream. Dealer tow bar fitted on purchase
Picked up a new trailer this week with LED lights. No surprise the lights played up. Interesting the car lights are fine and so are the brake lights on the trailer. So running / side lights dont work on the trailer. (car is fine at the same time). Same story with the indicators. They are working on the car but not on the trailer.
Returned home and got the ball mounted bike rack out. It has all incandescent lamps. No LEDs. Same story. Lights on the car are working. Indicators and running lights not.

Check all the fuses and can not find a fault there.

Is there a remote trailer control unit with a fuse I am missing or something else.

**TDIjeff** · 15-06-2014, 07:02 PM

Do you know if the car is fitted with a VW trailer loom with its own brain or a generic relay box ?
What format trailer plug, flat, round, 5 7 12 pin ?

**harks11** · 15-06-2014, 07:05 PM

No Jeff, not sure what loom was used. It was installed at purchase. Trailer plug is large round 7

**harks11** · 16-06-2014, 03:41 PM

Booked into the autoelec. so we will soon see

**Transporter** · 17-06-2014, 01:39 PM

Originally Posted by harks11

Booked into the autoelec. so we will soon see

Make sure that they're familiar with the late model VW electrics, otherwise they could do more bad than good, despite they're autoelectricians.

**harks11** · 20-06-2014, 05:19 AM

Well all fixed with the add of a load box if I run LEDs. It seems that the trailer adapter was programmed for the US and they reprogrammed it the faults went away. Given the car is six years old I am somewhat puzzled that that could be the case. Wondering if some sort of spike scrambled it.
However, time will tell. The Auto Electrician has one of the best reputations in Brisbane specialising in Euro cars. They charge to match.

**V10Touareg** · 17-07-2016, 04:48 PM

Originally Posted by harks11

It seems that the trailer adapter was programmed for the US and they reprogrammed it the faults went away.

Nope, that's dealer nonsense.

The intermediate LED 'black box' is the trick for LEDs; or an electric braking setup for towing - I have both.

I don't know why VW sales people don't ask this question when you order a vehicle.

Cheers,
Stu

**Umai Naa!!** · 17-07-2016, 05:33 PM

If only the brake lights are working, regardless of what lights are on the trailer, it means the trailer control module hasn't been coded to the car at all. Even once it's coded, you'll need the load box for LEDs.

Nonetheless, you've got it sorted which is great.

**V10Touareg** · 17-07-2016, 05:51 PM

Originally Posted by Umai Naa!!

If only the brake lights are working, regardless of what lights are on the trailer, it means the trailer control module hasn't been coded to the car at all.

That doesn't make sense, and is not true. What trailer control module? The LED connector? Nothing needs to be "coded", if the wiring is done correctly.

I acknowledge your 3,900+ posts, but this issue is an easy fix and should not be persisting.

Cheers,
Stu