Towbar Electrics again!

[Paynewright]

Hi,

I fitted my towbar ages ago (easy bit!) and have just ordered the 13 pin Westfalia electrics kit to finish off the job. This is a two part kit - firstly, the main 13 pin loom and secondly, the separate ignition switched live loom for the 12v auxiliary (fridge etc in the trailer). This second loom needs taking up to the battery.

I've read the instructions and it looks like I also need an additional loom as my van doesnt have a fuse box under the passenger seat. Again, this needs to go up to the battery. The main tow bar loom has three wires to connect into this 'extra' fuse box under the seat, which are fused individually. From the PFJones ebay advert this kit is 321455300001.


Now, also part of my electrics plan is to put a hefty fused feed from the ebox to under the passenger seat to run the small number of extra circuits I've added ( 2x USB, 12v socket, dashcam) plus some spare capacity. This would include ignition switch live feeds through auto relay(s) to kill the USB socket parasitic loads! This will eliminate the plethora of piggy back fuses in the mid lower dash!


So, my dilemma, do I.......

A) Install the tow bar electrics completely OEM and run 2 X wires up to the battery and additional oem fuse box under the seat AS WELL AS my own fused feed with associated fuse box & relays again under the seat?

B) Install my own feed and ensure sufficient capacity (load & fuse slots) to feed the 3 x main loom 12v connections and the switched auxiliary 12v feed with all these being connected to my fuse board under the seat.

C) Install all OEM wiring and use the VW / Westfalia fuse box kit to supply my own circuits (2x USB, 1x 12V 10 amp socket) - not sure whether the kit has enough capacity (load or slots)

D) Something else I've not thought of!



Any advice / insight welcome. Hoping @rod_vw will be able to help

Regards
Ian

 

[rod_vw]

Ian,

I'm assuming from your comments that you only have the basic engine battery set-up and no intention of fitting a leisure battery.

If that's the case I would be installing a feed from the 'E' box to a new fuse distribution under the left front seat. You seem happy to install a decent cable from the 'E' box which in my opinion should be 10sq mm at the least possibly as big as 16sq mm. Fuse location SA3 in the 'E' box is designated for second battery connection and sufficiently fused would be ideal for what you are suggesting.
However you run the cables please be sure that they are well protected from chaffing, there is a grommet to get access from the engine bay to the under dash area if that is your preference otherwise run underneath the van alongside the various pipes to the under seat area.
A good quality fuse box mounted securely will be good to connect the items that you are looking at. Access to that will depend on the seat that you have fitted. As I always have a swivel seat I make up a fuse / distribution box fully insulated on looms long enough to pull out backwards behind the seat box for maintenance.
Sods law says that if a thing is easy to access you will rarely need to get to it, if it's difficult you will often need to!

Remember what you think is the maximum you need today will be insufficient next year! Plan ahead.

Rod

 

[Paynewright]

Ian,

I'm assuming from your comments that you only have the basic engine battery set-up and no intention of fitting a leisure battery.

If that's the case I would be installing a feed from the 'E' box to a new fuse distribution under the left front seat. You seem happy to install a decent cable from the 'E' box which in my opinion should be 10sq mm at the least possibly as big as 16sq mm. Fuse location SA3 in the 'E' box is designated for second battery connection and sufficiently fused would be ideal for what you are suggesting.
However you run the cables please be sure that they are well protected from chaffing, there is a grommet to get access from the engine bay to the under dash area if that is your preference otherwise run underneath the van alongside the various pipes to the under seat area.
A good quality fuse box mounted securely will be good to connect the items that you are looking at. Access to that will depend on the seat that you have fitted. As I always have a swivel seat I make up a fuse / distribution box fully insulated on looms long enough to pull out backwards behind the seat box for maintenance.
Sods law says that if a thing is easy to access you will rarely need to get to it, if it's difficult you will often need to!

Remember what you think is the maximum you need today will be insufficient next year! Plan ahead.

Rod

Thanks Rod

 

[Paynewright]

So, still yet to fit the wiring kit which is a spring job now.

I’ve just ordered and collected the fuse box extension kit 000 055 212A and holder 7E0 937 503E. The fuse box kit comes with a 60A rated fuse and is connected to the battery +ve and has 8 slots with connectors. The screws to hold it to the front edge of the seat were out of stock N 107 214 01 so I’ll get these another time or use nuts and bolts.

Looking at the fuse box kit I believe this will satisfy my add on electrics needs namely two USB chargers and an aux socket at the back so I’m just going to fit it and re-work the plethora of piggy-back fuses, all of the cables route under the passenger seat.

Couple of observations - the cable takes an odd route and why not use the master fuse box under the battery? I think I’ll also run in convolute sleeving.

Ian

 

[Niknak]

Could you send me a picture of the connectors each end of the add on loom please looks to be the power cables which normally are a bit of an additional extra I’m just wondering as I have to fit a kit soon and it does not have the loom under the seat so want to make what I need to hook up cheers in advance

 

[Paynewright]

This is what is in the kit. The fuse holder uses the quadlock connectors to insert. I think this is fine for the towbar and/or a few extra minor circuits but not suitable for 2nd battery charging.

 

[Paynewright]

Clipped into the holder - all in £66 from VW.

 

[Niknak]

So literally just a power supply to a satellite fuse box then, does it just have a permanent feed ?

 

[Paynewright]

So literally just a power supply to a satellite fuse box then, does it just have a permanent feed ?

Yes permanent. The Westfalia tow bar electrics came as a two part kit. One is the main 13 pin kit with module (that needs the remote fuse box) and the second kit has a live going to the battery along with a relay for the aux live to the trailer. This is only live when the ignition is on.

So, I’ve needed three separate wiring kits to fit fully functioning tow bar electrics. Some would get away with one kit if they didn’t need the trailer fridge feed and had the under seat fuse box already.

I’ll do an install write up when I fit it all!!

Ian

 

[Joseph]

sorry to hijack your thread, but does the trailer connector have an isolation switch (reed switch in the flap etc) to disconnect the rear parking sensors when the trailer is attached, to stop them blaring at you?
Reason I ask is I have fitted a bike rack semi permanently to the rear of my van and it causes my rear sonar to scream, i have a trailer socket but its just a basic one (no switch) so i assume even if i did tow a trailer the sonar would scream at me.... is there an appropriate connector in there to wire a switch to disable the sonar?

cheers
Joseph

 

[Deaky]

sorry to hijack your thread, but does the trailer connector have an isolation switch (reed switch in the flap etc) to disconnect the rear parking sensors when the trailer is attached, to stop them blaring at you?
Reason I ask is I have fitted a bike rack semi permanently to the rear of my van and it causes my rear sonar to scream, i have a trailer socket but its just a basic one (no switch) so i assume even if i did tow a trailer the sonar would scream at me.... is there an appropriate connector in there to wire a switch to disable the sonar?

cheers
Joseph

When you fit a vehicle specific towbar loom the parking sensors are disables automatically when anything is attached to the socket. IRS done via Canbus. You could add a switch to the power supply for the parking module. The wire is purple/black in pin 1 of the black connector on the PDC module. Doing it this way will probably throw errors up though.

 

[Joseph]

When you fit a vehicle specific towbar loom the parking sensors are disables automatically when anything is attached to the socket. IRS done via Canbus. You could add a switch to the power supply for the parking module. The wire is purple/black in pin 1 of the black connector on the PDC module. Doing it this way will probably throw errors up though.

Legend, i thought it may have been something along those lines, I'll make up a little dummy plug with some resistors and see if that works

 

[Paynewright]

I have all the wiring parts for mine but waiting for spring as non essential!

Looking at the westfalia 13 pin socket it has 3 connectors in addition to the 13 which I assumed was some sort of switch so it knows something is plugged in.

Remember as well the van needs programming to update the towing options using VCDS.

Ian

 

[mmdave]

Hi Ian, I'm looking forward to your write up because I'm struggling with my own towbar wiring. As you say, fitting the towbar was the easy bit. Has it been spring-like enough to complete the wiring?

I'm planning on using your option B because I added a 12V feed that terminates under the seat in the past. I have the non trailer prep wiring kit and I have terminated it under the seat rather than at the battery and am taking all the 12V supplies from my existing feed.

I need to feed the can bus and brake light wires to the BCM under the steering wheel. I have routed the wires under the carpet already, along side the existing loom. The problem that I have is that I'm struggling to get access to the BCM plugs - I can't believe anyone could make reliable connections in such a confined space! I really wish I had specified trailer preparation.

I have had a look at the wiring diagrams for my van and the convenience can bus seems to be connected to the radio so I plan on making the can connection at the radio and the brake light switch connection is easily available near the switch on the master cylinder under the bonnet. Does this sound a sensible alternative to making connections at the BCM? Has anyone got a better solution?

Thanks, Dave.

 

[Niknak]

Be careful as there are two brake wires, the plugs come out easy on the bcm to make the connections that are needed, my van had an incorrectly fitted wiring kit connected to the incorrect brake wire which back fed the switch and kept killing them when the module was woken up,

 

[mmdave]

I had another go at making connections at the BCM. I did get the plugs out and I there are a couple of wires with the same or similar colours so that's a good tip. My trailer instructions tell me to use pin 43 but they don't have a pinout (I did get that from the wiring diagrams online). The brake wire is buried in the middle of the bundle so I gave up for the 2nd time and spent a long time trying to reconnect the plugs. Connecting at the BCM too difficult for me!

I connected to the brake wire near the switch (soldered and waterproofed rather than using the splice supplied with the towbar wiring kit) and the CAN bus at the radio which is easy to remove and has a nice small loom to connect to (I have an adapter to connect an amp which makes connecting the CAN signals even easier) and I'm happy to report everything is working as expected.