Towbar Information

[limiteded]

In reference to a b7 alltrack, and the genuine towbar/ wiring and control unit from VW aust

I went to test my genuine vw towbar/wiring harness for the presence of a permanent positive(terminal 30), for a brake controller on another trailer.
The permanent positive was not existant, not from the euro 13 pin plug - pin 9.

Because i have the current flow diagrams avaliable from erwin, i was able to know what to look for. After a fair bit of investigation including vcds diagnostics and testing, i figured i had to pull the trim apart and have a look at what was wired into the trailer control unit(j345), which is behind the luggage area left side trim piece, on the wheel arch.
Note i advise to use the manuals so that u know where and how to remove this side trim as alot of other trim/parts are required to be removed.

it turns out that the genuine wiring harness from the 13 pin europlug, to the j345, is wired for everything except the permanent positive-pin9, another earth connection- pin 11, and a charge line - pin 10. Ie these wires are not connected to the j345 or ground, at the control unit location on the wheel arch.
these 3 wires are terminated into a separate 3pin plug, which is left floating next to the control unit. The VW instructions state u have to buy a westfalia wiring harness ( 300 025 300 113), and route it to the front of the vehicle to the fuse box SC.

anyway because i have all the VW wiring terminals, crimpers, tools and knowledge, i was able to take the pin 9 wire, cut it at this floating 3 pin plug, and crimp a new terminal on it suitable for the j345 16 way connector, and insert the permanent positive wire into the correct terminal of the j345, and get my permanent positive. In the vcds coding you can select whether you want this pin always active, only active if a trailer is connected, or not active at all. Std coding is always active. I think that the j345 will auto turn it off if the battery volts are to low.

i also bonded the earth cable, and connected a wire to that charge line mentioned, and have run the wire to the front of the vehicle inthe passenger footwell, since i had all the trim removed, i thought why not. When i decide its necessary i may finish it and connect it somewhere.

also be aware that the 13pineuro to 7 pin flat aust/nz converter from vw aust is not wired for the permanent positive to pin 2 of the flat. It needs to be modified to get this. But ive made my own ones up also with the 12pin flat connector.

[Euro Car Upgrades]

good on your Limiteded.
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You seem like you know what you are doing anyway. But there will be a lot of people without the access to ELSA or Coding Information.