Fitting a Towbar

Alan

Me!  Not many of us tow with the BMW's on here. Mine certainly makes a great tug.  Hauling a caravan up the M74 inclines overtaking cars was nae bother.

I've fitted a Westfalia detachable bar to my E60 and a home made wiring loom. I was quoted a mind bending £1200 for the job from Harry Fairbairns!

The OEM bar is Westfalia anyway except mine cost about £250 inc VAT and not the £300 exc VAT the dealer wanted for the bar alone.

All in all it cost me just under £300 by the time I paid for a few bits and bobs.  I fitted it myself in less time I reckon HF had allowed for!

The most difficult job was removing the piggin' bumper!

What I did was by a bypass relay from Ryder Towing which was supplied by the company I bought the towbar from for about £20.  I bought a length of 7 core cable and a black socket 12N from Halfrauds and made myself a home made wiring kit.

The lights in your BMW flash. They are not on all the time but flash faster than the naked eye can detect but to you and me they appear on.  The ECU sends pulses of power thru the wires to the bulbs.  This means BMW can fit thinner wiring and save £2 of copper on each car which adds up when you make a few cars a year.  When you add additional lights, i.e. when towing a trailer to these 'pulsing' systems it can upset the cars electrical system.  

To get round the BMW's wiring system you need to fit a bypass relay.  It works by receiving a signal from the wire that supplies each rear light.  Once a signal is received it then switches on a 12V supply from the battery which then sends the power down the 7 core cable to the socket and then into your trailer lights. 

The bypass relay only draws a few milliamps more from the cars circuits so the car does not detect the extra load as this will be within tolerances.  A 21W bulb from one manufacturer will draw more current that a 21W bulb from another, so there has to be 'give' in the system. Using a bypass relay means the cars bulb failure system is unafected by the trailer lights.

The bypass relay connects to the cars wiring system at each rear light cluster.  You tap into each relevant wire using a red piggy back connector (Halfrauds again, the blue ones that you get with the 7 core cable are too big) one at a time and take a wire back to the bypas relay which is mounted in the boot.  The bypass relay requires a fused 12v feed.  I took this from the back of the fuse box which is mounted in the boot of my E60 just above the battery.  You then connect the 7 core cable to the 12N socket, pass thru the boot floor using a rubber gromit and then wire the 7 cores into the relevant connection on the bypass relay.

I removed part #6 from my car and repalced it with part #7 which required a further bit of filing and cutting to fit with the towbar.  It means I can replace the original part when I do come to sell it in many years to come. Parts #2 (same page as link above) get removed and the towbar replaces the need for this and part #1 then gets bolted to your towbar.  I would imagine the 1 Series will not be too different.

Go on the Westfalia website and you will be able to download the towbar fitting instructions.  I spent a bit of time Googling towbar wiring (I don't have the links on this PC sorry) and got my head round it that way plus I had a genuine Ford Mondeo towbar wiring loom (which cost my dad about £120) to figure out how a bypass relay would work with all the connections to each light and then onto the socket. 

The wiring loom that BMW would fit essentially consists of a plug and play system which will include connectors to connect directly into the cars wiring loom at each light cluster and will have a built in bypass relay but it costs a chuffin' fortune.  I built my own equivalent loom for about £40.

I'm going to the Rolling Road day on 15th March in Bonnybridge, if you come along I'll happily show you the wiring loom I made up which is installed and works like a charm in the boot of my E60.

Let me know what you think.

Andrew

You're very welcome Alan.

I got my towbar from these guys £10 for next day delivery I think.

http://www.towbarsdirect.co.uk/

and I spent a bit of time reading this guys website.

http://www.rydertowing.co.uk/default.htm

Also have a read of this

http://www.rydertowing.co.uk/downloads/pdf_checklists/Practi cal%20Guide.pdf

Something to bear in mind for the future.  All caravans from 2009 onwards will come with a 13 pin plug and not a 12N and 12S plugs.  Will probably only be a matter of time before trailer manufacturers start putting 13 pin plugs on their trailers, purely to be compatible with caravans.

I might be able to make it to the March meet which will be a couple of weeks before Bonnybridge.

If you need to know anything else, just ask.

Andrew

Hi Alan

Mibbie worth bearing in mind the cost of the towbar if you are going to replace the car in 18 months unless of course you are going to buy another 1 Series.  Although a 4 year old 1 Series shouldn't pose any problems I wouldn't have thought.

I was prepared to pay for a Westfalia bar as I don't plan to change the car for a number of years.

Towbars direct were certainly very good.  The straight away recommended the Westfalia removable bar for my car.  They even told me the the sales rep from Witter said the the Westfalia removable towbars were the best!

Let me know how you get on.

Andrew

That is a pretty good price!

I suppose the bar for your 1er will be smaller and lighter (which wouldn't be chuffin' difficult) than the one for my 5.

I doubt that much will go wrong with it.  I wouldn't use the Auto Stop Start that just seems wrong to me but I would be fairly sure that BMW have ironed out the turbo problems by now that wounded reliability on the E46 and E39 oil burners.

Just bear in mind my offer to show you the wiring loom at the rolling road day.

Any questions, just ask.

All the best with fitting it.

Andrew

Alan

Wiring colours from my 5 Series.

The pin numbers are the number marked on the wiring loom plug that plugs on to the back of the bulb holder.

Nearside

Earth, Pin 1, Brown

Fog, Pin 2, Yellow/Black

Reverse, Pin 3, White/Yellow

Brake, Pin 4, Grey/Green

Indicator, Pin 5, Blue/Brown

Tail, Pin 6, Black/Red

Offside

Tail, Pin 6, Black/Brown

Indicator, Pin 5, Blue/Brown

Brake, Pin 4, White/Brown

Reverse, Pin 3, Yellow/White

Fog, Pin 2, Yellow/Red

Earth, Pin 1, Brown.

Standard Notation and colours for a 12N socket

Nearside Indicator, Pin 1 (L), Yellow

Fog, Pin 2 (54g), Blue

Earth, Pin 3 (31), White

Offside Indicator, Pin 4 (R), Green

Offside Tail, Pin 5 (58r), Brown

Brake, Pin 6 (54), Red

Nearside Tail, Pin 7 (58L), Black.

I linked the bypass relay to the relevant wires above using small gauge wiring that I use on my model railway layout.  I had wire that matched the standard colours.  For example the nearside indicator has a length of yellow wire linking the blue/brown wire on the car to the bypass relay.  This then matches the yellow wire that then goes to the 12N socket.

HTH

Andrew

Alan330ci wrote: Already started on making the loom and just need some more bits from Halfords to do the power side as im going to use the power socket in my boot as the switched 12v feed as i dont want the relay being live all the time.

The power socket in the boot might not be man enough.  It would need to be fused with at least 15 amps to cope with the power.  You need the bypass relay to be live 24/7 so that parking lights will work etc.  If the power socket in the boot is only live when the ignition is on, you aren't using the correct thing to power the bypass relay.  If the battery is in the boot, use it directly with a fuse.  It prevents overloading other circuits.

Alan330ci wrote: Just one more question did you use Scotchlocks or something else when connecting to the tail lamps?

I used the red scotchblock connectors from Halfrauds.  The blue ones from Halfrauds are too big for the BMW wiring.

Keep the questions coming.

Andrew

Some good tips there Alan, soldering will give a much better connection than any scotch blocks.

Glad I could help you out.

Saying that, my dad is just about to buy a new caravan which now comes with a 13 pin plug, which means the car needs to have a single 13 pin socket.  With the type of towbar we have you would struggle to install two sockets on the flip mounting for both 12N and 12S sockets.  With a single 13 pin socket you get both 12N and 12S electrics in one single socket.

Any other questions, do not hesitate to ask.

Andrew