13 pin vehicle Specific Vs. 7 Pin Bypass realy

**BMurr** · 25-02-2011,10:00 PM

Just recently took delivery of a new westfalia towbar with electrics. Only problem is that it comes with the vehicle specific 13 pin kit and I really only need a 7 pin kit for towing small trailers. As far as I can tell the 13 pin vehicle specific kit is only really usefull if I am towing caravans, which is not likely for me. The vehicle specific kit also takes a fair bit of work to install and it seems to me to be a big waste of time if I don't really need it. i also have a relay kit so that I can do the simple relay type of wiring for 7 pin setup. Am I missing something here in terms of some great advantage to using the vehicle specific kit or am I really best to just go with simple relay and 7 pin setup?

**phil miller** · 25-02-2011,10:08 PM

i think its a canbus adaptor aswell mate so if you dont use it you will have issues with your canbus/bulb out warning

**BMurr** · 25-02-2011,10:17 PM

Cheers Phil.The bypass relay kits instrcutions says that it only samples a very small current from the vehicles electrics such that it should not trigger the bulb warning system. I guess I could take my chances with the relay and if it doesn't work then fit the specific kit, although I see another poster today has with problems with his relay kit. Are the relays problematic, do they tend to act up over time?

**BMurr** · 26-02-2011,11:59 AM

I've also now seen some posts about LED trailer lights triggering bulb warnings with OEM vehicle specific systems and I've just bought some submersible LED trailer lights for a boat trailer so steering towards fitting the bypass and seeing how that goes but keep the OEM kit for a few months and fit that if any problems. Decisions, decisions.

**A4 Lad** · 26-02-2011,12:45 PM

If its a case of your display saying that you have bulbs out when the trailor is on, I would live with it as you know its only because the trailor is attached that it is saying that ( if you know what I mean lol )
PS - All LED bulbs will mislead the computer in thinking that there is a bulb out so I would'nt base your decision on that

Sent from my iPhone using Tapatalk as I forget how to use a full size keyboard !

**BMurr** · 01-03-2011,05:37 PM

Ok. eventually decided to go the simple route of 7 pin electrics with bypass relay. Taking bumpers and trim off is straightforward, putting bumpers back easy but those side trims are a bit of a pain with the clips needing to be lined up, long fingers a bonus. There might be a better way of douing it but I've pout the relay on left hand side and its hidden neneath a panel near vent under the false floow. The right side flasher lead and the relay power( from cig lighter power in boot) come from right side so two wires trailing across, all taped up but not visible as neneath trim panels. I'm glad it's over and I would not want to be doing it again for a long time. Took a while to figure which wires to tap into with those scothlocks. All works fine and no warning lights on the dash. I must get around to disposing of the westfalia 13 pin car specific kit over next few weeks. I decided against 13 pin anyway as all the trailers I see over here in Ireland are 7 pin, I even went to an audi dealership and looked at what was gojing onto their new cars and it was 7 pin. 13 pin probably good for continent and of course if you are towing something that needs independant battery charged such as a caravan.

**fisher72** · 06-03-2011,10:09 PM

Originally Posted by BMurr

Ok. eventually decided to go the simple route of 7 pin electrics with bypass relay. Taking bumpers and trim off is straightforward, putting bumpers back easy but those side trims are a bit of a pain with the clips needing to be lined up, long fingers a bonus. There might be a better way of douing it but I've pout the relay on left hand side and its hidden neneath a panel near vent under the false floow. The right side flasher lead and the relay power( from cig lighter power in boot) come from right side so two wires trailing across, all taped up but not visible as neneath trim panels. I'm glad it's over and I would not want to be doing it again for a long time. Took a while to figure which wires to tap into with those scothlocks. All works fine and no warning lights on the dash. I must get around to disposing of the westfalia 13 pin car specific kit over next few weeks. I decided against 13 pin anyway as all the trailers I see over here in Ireland are 7 pin, I even went to an audi dealership and looked at what was gojing onto their new cars and it was 7 pin. 13 pin probably good for continent and of course if you are towing something that needs independant battery charged such as a caravan.

sorry to hijack your post fitted tow bar to my a4 2004 s line every thing work apart from the brake lights can you tell what wires went to were so i can check cheers paul

**A4 Lad** · 06-03-2011,10:14 PM

Standard tow bar wiring ( from socket ) :

Blue - Fog Light ( you dont need )
Red - Brake Lights
Black & Brown Joined - Side Lights
Yellow - Left Indicator
Green - Right Indicator
White - Earth

**fisher72** · 06-03-2011,10:17 PM

must have read the instructions wrong it said the brake and tall light was all on one wire so you only had to use the red cheers for your quick reply Paul