Tow bars & bike racks

[passatpout]

OK, I'm after a little bit of help here... for Christmas, Santa (well, my brother) was kind and delivered a towbar-mounted 4-bike rack, which sits nicely and was easy to install, although it means that I had to take off the rubber surround at the base of the towbar.

Now for the tricky bit - the legal stuff. I need to get a bike rack number plate, which the good folks at Vicroads have promised to deliver to me in 14 days, and for that privilege they only required me to hand over $27 ($7 cheaper than NSW..). However, if I use said bike rack at night, I need to illuminate the plate.

So here's the choices:

1) Use the existing adaptor that came with the car, and make up a set of lights for the bike rack that plug into the flat 7-pin connector.

2) Make up a new harness, using the same type of plug that's on the car (the 13-pin round).

3) Make up a new harness, using the 13-pin connector, that will act as a double adaptor and let the bike rack and trailer lights operate in harmony, without exceeding the load limit of the car power supply. If I do this, then I'll get the benefit of being able to run an extra power wire to a trailer to keep a car fridge there, rather than taking up space in the boot.

Finally, does anyone have the details of the round plug? Judging by its size and type, I'm tipping they'll be about $80 each, if available at all.. almost a military-style, but not quite..

Thanks all,

AP

[tryingavw]

OK, I'm after a little bit of help here... for Christmas, Santa (well, my brother) was kind and delivered a towbar-mounted 4-bike rack, which sits nicely and was easy to install, although it means that I had to take off the rubber surround at the base of the towbar.

Now for the tricky bit - the legal stuff. I need to get a bike rack number plate, which the good folks at Vicroads have promised to deliver to me in 14 days, and for that privilege they only required me to hand over $27 ($7 cheaper than NSW..). However, if I use said bike rack at night, I need to illuminate the plate.

So here's the choices:

1) Use the existing adaptor that came with the car, and make up a set of lights for the bike rack that plug into the flat 7-pin connector.

2) Make up a new harness, using the same type of plug that's on the car (the 13-pin round).

3) Make up a new harness, using the 13-pin connector, that will act as a double adaptor and let the bike rack and trailer lights operate in harmony, without exceeding the load limit of the car power supply. If I do this, then I'll get the benefit of being able to run an extra power wire to a trailer to keep a car fridge there, rather than taking up space in the boot.

Finally, does anyone have the details of the round plug? Judging by its size and type, I'm tipping they'll be about $80 each, if available at all.. almost a military-style, but not quite..

Thanks all,

AP

dont have all the answers but to ensure you dont overload the wiring use LED globes for the number plate lights. they us MUCH less current. plus are quite bright. heres a link to some ive ordered to replace interior lighting on the wagon:
http://cgi.ebay.com.au/ws/eBayISAPI....m=400021535551

also the round plug seems to be a euro standard ( bmw had one and provided an adaptor cable as well) so should be easy to find details.

[passatpout]

Funnily enough, I was about to edit the post to ask about using LED lights on the trailer. I was thinking about that, then saw some posts on other forums that they can cause grief with cars that use electronics to control trailer lights, as opposed to straight electrics.

But that clears up the question quite nicely about whether I can use them or not..

From memory, brake light load is 84W max (4x21W globes), tail and clearance lights are 40W (8x5W), indicators are up to 42W (2x21W globes). LEDs should be much lower, but are a bit pricier to buy.

Now, if only I can find the plug details. I wonder if it's worth getting a second loom from VW, then I can cannabalise that into what I need..

[tryingavw]

I wonder if it's worth getting a second loom from VW, then I can cannabalise that into what I need..

try ebay or the web first. vw will sting you for one i reckon.

[STV4SYT]

If you only need to light up the number plate, im sure a small LED with a 9v battery mounted behind the plate would do.

Or even cannibalise one of those solar garden lights.

[vanDub]

Be careful using LED lights. They sound great in theory but I recently had issues with my trailer lights working intermitantly on the VW after the towbar and electrical harness were replaced by the panel shop after a rear ender. The trailer lights worked fine on my other car.

The Dealer tested the VW electrical harness working fine using a test board made up with standard (non LED) trailer lights. When discussing what could be wrong elsewhere in the trailer wiring that could cause them to work on one car but not the other, the first thing he asked was if the trailer had LED lights.

He advised that the VW harness is set up to work with standard incandescent trailer lights and is very touchy with LED lights as they need to be wired with resistors to restore resistance to match non LED lights. It can take a lot of trial and error to get the setup to work with LEDs.

As it turned out my problem was fixed by replacing the 5 core wire from plug to the rear terminal block that then feeds to the lights, even though the old wire was OK. A subtle variation in wire resistance between the new and old wire was enough to affect the lights working when connected to the VW.

[tryingavw]

Be careful using LED lights.\

He advised that the VW harness is set up to work with standard incandescent trailer lights and is very touchy with LED lights as they need to be wired with resistors to restore resistance to match non LED lights. It can take a lot of trial and error to get the setup to work with LEDs.
.

.adding LEDs in parallel with existing incandescents is OK. what happens is the electronics delivering the 12v actually monitors the load for a certain current range . when you put LEDs in parallel the load wont change much at all. But depending on the circuit, if you double the load ( ie 2 incandescents in parallel) depending on the globes the circuit may decide you have an overload. its a gadget siemens developed called a VFET - basically your lights are now driven by a fancy transistor with additional monitoring circuitry. forget old tech relays!

the main idea is if the globe is gone, the circuit will not see a current and warn you of a blown globe.

but this new and exciting technology does create side effects ( the main one you need to spend a mint getting their trailer wiring!) there are ways around this, but they have risk of voiding warranty. I think Lumen make an interface which taps the voltage and provides an isolated drive for additional lights.

i plan to fit a towbar some stage and will go down this route very carefully!

sorry if i got a bit technical there . but i'm an electrical engineer and have looked at VFETs.

[saabman]

The Part from Lumen is L-1870T.

[stuben]

Hi I have a 11/08 Passat 103 TDI with the Dealer fitted tow bar. Is anybody able to tell me where to pick up the signal for the brake lights for the electronic trailer brake control considering this vehicle has no brake light switch on the pedal. Also, I have the wiring diagram for the 13 pin plug if someone is chasing it.