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 http://www.realoem.com/bmw/showparts.do?model=NB32&mospid=47756&btnr=51_4919&hg=51&fg=15 - part #6 from my car and repalced it with http://www.realoem.com/bmw/showparts.do?model=NB32&mospid=47756&btnr=51_4919&hg=51&fg=15 - 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
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