[BMWBen]

Bought one for my 330d - westfalia removable. Can't get it fitted at weekends so elected to do it myself

Not fussed about getting the bumper off and fitting the bar, but unsure about the electrics. I'm going to be rigging up a bypass relay.

1. Does anyone know where I can find the wiring diagrams for the rear lights?
2. Where am I going to get a 12v feed from?

Even if you didn't fit yourself, if you've got a relay setup it would be awesome if you could have a look and tell me which wire goes where. Virtual beer available!

Cheers!
(reposted this - first post was in the general bimmerpost by accident )

[BMWBen]

shameless bump

[200Duece]

Try and contact your local bmw store for some help. I know that with the X5's when you have a hitch installed and use the oem wire plug connected to the actual trailer that the DSC knows to operate accordingly. This might not even by an option for a non Xdrive car. But if it is then I think it would be worth the extra work. The trailering version of DSC is GREAT.

[fbe92]

Have you seen this one? I think it's a South African BMW option. Pretty cool.

http://www.e90post.com/forums/showpo...8&postcount=51

I've also seen some other, more low tech solutions when I did a search a while back. It sounded a bit expensive, and it looked like there was some welding/drilling typically involved.

[teemuturunen]

First: the car has to be fully updated to the latest ISTA/SSS version... then you can install the towbar wiring harness (get the OEM harness) WHAT 330D WAS THIS??YOU HAVE PDC SENSORS??? you just can't connect the wires to the light's...if you do that,you will have lot of problems and car will not go to sleep...

[BMWBen]

Not going to connect directly to the lights - going to connect through a smart relay that can understand the different signals that get sent down the light wires, without drawing any current (well, a tiny bit of current).

I'm not fussed about that really - just where to get the power for it all! Could take it straight off the battery but I'd rather use a feed that was switched from the ignition.

Does anyone know where the OEM wiring harness gets connected? I expect there'll be a voltage feed I can use there...

[BMWBen]

Originally Posted by teemuturunen

First: the car has to be fully updated to the latest ISTA/SSS version... then you can install the towbar wiring harness (get the OEM harness) WHAT 330D WAS THIS??YOU HAVE PDC SENSORS??? you just can't connect the wires to the light's...if you do that,you will have lot of problems and car will not go to sleep...

I have PDC sensors, but not fussed about them being turned off automatically - I can always just push the button on the dash.

Used a relay setup taking signals from the rear lights on my e60 and that worked really well. If someone hadn't stolen it I could have a look and see where the fitter sourced the power from

[teemuturunen]

I can send you info how to install OEM harness... but if you do not want to install Oem....you can take the power from fuse box.... but the fuse has to be one what goes to sleep (otherwise IBS sensor wont work and you will have flat battery cause the powermodule wont let the car go to sleep) sleeping fuse can be found when you turn off the ingnition and wait 15-30min

[BMWBen]

Hmmmm, fusebox is at the other end of the car! Long way to run a cable! Would be cool if you could send me the OEM harness instructions, might just splash out to make things easier...

Or I could steal the 12v feed from it

[CirrusSR22]

I installed a towbar/hitch on my E36 and used a smart power converter like you were mentioning. Here's link I found of someone installing a hitch on an E39 540i. http://gunsmoke.com/cars/540i/hitch/

It really is a simple process, once you find the correct wires going to the proper lights too get the logic for the system. I just tapped off the battery for power. I took the power wire off the converter, installed an inline fuse holder, then a ring terminal and connected it directly to the battery. It's easy since most BMWs have the battery in the trunk so it's a very short run. My E36 318ti has the battery under the boot/hood so I did run a power wire all the way front to back.

If BMW has a plug-in solution, that would be great. Finding trailing info for BMW cars in the US is nearly impossible so I went with the aftermarket converter.

Not that this applies to your E90, but once I removed the trim in the back of my trunk, the wiring bundle was very easy to find.



I made a metal bracket (the light brown thing) and stuck the power converter to it.

[teemuturunen]

the oem wires take the power and wake-up line in front fusebox...other wires goes to extra brake light, CAN BUS near rear seat's and PDC unit. Installing towbar to e39 e46 e36 is much diffrent then install it to e9x or e6x

[BMWBen]

Had a bit of a dig around the battery this morning - the distribution box that fits on top of the battery can have addition plugs added to it, but I think the connectors will only take a much bigger cable than I need.

So I reckon I'll see if I can drop a ring connector onto the +ve terminal under the distribution box, wire in an inline fuse, then onto a switch so I can isolate and the then relay. Then run the -ve back to the -ve battery terminal, which I think is exposed.

Anyone see any issues with that? Only problem I might have is the fitting of the distribution box over my connector, it all seems a bit well packaged. On the plus side with that huge bit of plastic in place there isn't going to be anything that can be shorted out.

If it doesn't work I guess I'll just take an additional plug from the dist box with a big cable, then downsize it as I pass it through an inline fuse.