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Discussion Starter · #1 · (Edited)
I installed a Westfalia OEM hitch on my 335d (e90) and I figured there might be others interested in doing the same. If you are one of those people who just can***8217;t wrap your head around a BMW sedan towing anything, please move on. I***8217;ve all ready made that decision and know for a fact these cars can tow with out any negative repercussions to the car, its frame, or its engine.

Anyway, I purchased my hitch and the wiring from pfjones in the UK (just google them and you***8217;ll find them). These are OEM to BMW (which should also be an indicator that these cars can tow) and specifically to the E90/E91 model year 2005 and up.

I purchased the following parts:

Westfalia Detachable tow bar (Tow bar = hitch in the UK)
Part #: 303330 (because I have a 335d I had to have this tow bar modified by a welder I***8217;ll post pics later of the work done) The ball is 50mm which I think is just a hair smaller than a 2" ball but not a big deal.

BMW 3 Series Dedicated Electrics: 7 pin E90/E91 2005 on All Models (you will need a 7 pin to 4 pin adaptor but they are easily found on the internet and cost about $8)
Part #: 303460300107
BTW you DO NOT need to have any programming done after the install.

Extra exhaust brackets for 335d. You do NOT need this if you don***8217;t have a 335d.
Part #: 303240600015

And you***8217;ll use the following tools:
18mm deep socket with extension
10mm socket
8mm socket
T50 Torx
T25 Torx
Flathead screwdriver
Phillips screwdriver
Utility knife
Trim removal tools (plastic preferred)
Pliers

I've attached the PDF manuals with only the English and E90/91 instructions.

Total cost with shipping was about $700. It arrived in about 5 business days. Yes, pricey, but the hitch is completely hidden as are all the electrical wiring. It also comes with a BMW electrical junction box and doesn***8217;t mess with the car***8217;s touchy computer and wiring (if installed correctly). It will also works with your PDC if you have it installed.

In addition this is a fully functional hitch and can tow at maximum capacity. Which is something like 4000lbs. I***8217;ll never tow anything close to that so I don***8217;t really know. The hitch literally replaces the rear bumper and is in fact far beefier than the original bumper.

Surprisingly the install wasn***8217;t that complicated once I knew what I was doing. I could probably do this in about 2-3 hours now. All told I put in about 6-7 hours going very slow and going back and forth on the computer looking up stuff after making some mistakes or simply not able to do it as others advised.

I***8217;m writing this DIY to collect all the information that you will need to do this in one place. I am also adding some of my own tips and tricks that I learned along the way as some info (like the westfalia wiring) doesn***8217;t really exist.

I***8217;ll only be providing pictures where something isn***8217;t that obvious and where others haven***8217;t provided it. So now on to the DIY part.

Part I Installing the Tow bar (hitch)

I***8217;m not going to go into to much detail here about preparing to remove the bumper because there is an excellent you tube of this process:

youtube video

DO NOT follow his instructions for removing the bumper skin. His method is not correct and you***8217;ll end up banging your head for too long. See below.

To sum up the relevant parts of the video: take out the tool kit holder/battery cover on the right (plastic turn latch), take out the floor cover of the trunk, take off the left cover over the rear lights, take out the rear lights (8mm x3 for each), take out the ***8220;felt***8221; panel covering the right wall to expose the wiring (plastic rivets), take off the plastic cover on the rear of the trunk (covering the latch, 2 philips screws are hiding underneath two plastic covers, just pry off with one of your handy trim tools, 4 plastic rivets), undo all of the bolts (8mm) holding on the bumper skin per the video and the two hidden screws (T25 torx).

In regards to the plastic rivets, lots of people complain about these but do yourself a favor and buy some plastic trim removal tools. You***8217;ll need them later anyway. They won***8217;t scuff your car like a screwdriver and they work very well for this task. The plastic rivet is a two-piece part and you have to pull out the ***8220;nail***8221; for the whole rivet to come out. Use the trim removal tool to pry in between the two parts.

If you have PDC I think you need to worry about that somewhere around in here but I wouldn***8217;t know.

Ok now that you have all that off, now you need to remove the bumper skin. This is actually fairly straightforward but the first time you do it you might not think it will go. Follow this guy***8217;s instructions. They are dead on and your life will be so much easier. You also won***8217;t break any of the ***8220;tabs***8221; that everyone complains about. They don't mention this but you may want to gently pull on the side skirt of the bumper skin on the bottom to undo some clips that are in the middle of the panel. You'll feel them pop off with a little force. Again this in the middle of the panel on the side. Do not pull at the top of the panel as you don't want to break those tabs. They are around the area and height of where the DEF tank filler cap is on the left side of the car and they exist on both the left and right panel. Sorry no pic of those.

All you really have to do is undo the two tabs under each tail light assembly (they are hidden under this plastic piece. Just pry with those plastic trim tools and you***8217;ll be able to get the tabs undone. Here's a pic of the two tabs on the left side. See the other pic below to get an idea of the plastic piece under the tail light assembly where the two tabs are held.



Next grab the bumper skin at the wheel well and at the back of the bumper and pull firmly back. It really helps if you can have a helper do the exact same thing on one side while you do the other. This is the part where you are not exactly sure it will go but when it happens it just all of the suddenly happens. It is not a gentle sliding off. It literally pops off. You will at first notice some very small progress at the back if you look at the tabs at the back and how the skin has slid back a small amount. Next thing you will probably be on the floor with your friend and the bumper skin in your hand wondering how that happened. It now takes me about 5 minutes to do this and I***8217;ve done it 4 times and no tabs broken.

Here's a pic of the skin off with proof of the tabs not being broken



From here the bumper removal is very straightforward. Don***8217;t forget to undo the screw(s) holding on your mufflers (again 8mm). It***8217;s easier to undo the screws than to try to take off the rubber mount. Use the 8mm again. The 335d has a left and rear exhaust so I had two screws.

You***8217;ll need a deep 18mm socket and an extension to take off the bumper. The deep socket will barely fit but it does work. The bumper is held in place by 6 bolts. Don***8217;t forget to take off the rubber exhaust mounts and also the bolt mounts to use them on the new bumper.

Here's a pic of the old and new bumper together.



Before you put on the new bumper go ahead and pull through the wiring harness from the battery well on the right side. You***8217;ll be installing the brain in the battery well. My car all ready had a hole in the battery well from where the wiring for the DEF tank sensors, etc, were coming across. If you have PDC then you***8217;ll also likely all ready have wires coming out, so no drilling. If you have none of that then you***8217;ll probably either have a plug covering the hole or you***8217;ll have to drill.

The wiring kit comes with a rubber plug that you will have pull over the wire and then cover the hole. Per the instructions I had to cut the plug to also include the wires for the DEF tanks. There is a strip of waterproof gooey stuff that you use to fill in the gaps and waterproof where you cut the plug. Pull the harness through but leave yourself about 1 ft on the other side so that you have some extra cable to mount the wiring module. Use some of the plastic zip ties to guide the wiring harness on the bumper. Be sure to stay away from the exhaust.

Here's a pic after I've pulled through the wiring and plugged everything back up. I also circled the plastic piece that holds the two tabs that you need to undo to remove the bumper skin. There is one under each light assembly. Also circled are the mounting bolts for the bumper and the end of the wiring harness for the trailer.



Go ahead and install the new bumper/hitch. Installing the provided exhaust brackets is very straightforward and in fact you can***8217;t screw it up based on how they are mounted. Follow the instructions for connecting the wiring harness to the plug and mount on the bumper. I would wait until you are done with the complete wiring harness before you put on the bumper skin so you can check your connections (remember the part where I***8217;ve taken off the skin 4 times?).

here's a pic of the exhaust bracket installed on the new bumper



Ok now it***8217;s time to do the wiring. This is the part that Westfalia***8217;s instructions just aren***8217;t that clear at first. It***8217;s like reading hieroglyphics. Once you understand the alphabet though the instructions become clear. First, understanding the wiring diagram.

I***8217;ll list the numbers on page 2 of the Westfalia instructions and explain what I think I know and what they match up to on the wiring on your car. Keep in mind there are two installation instructions. One for an E90 with PDC and one without. I don***8217;t have PDC so I followed steps 3b, 14, 15, 16, 17 and ignored the steps listed below as well as following the rest of the instructions. i pertaining to both. If you have PDC then you follow steps 3A, 10, 11, 12, 13 and ignore the list above, and also follow the remaining instructions. See the attached wiring PDF.

Westfalia Harness <---------------->BMW wiring/location

1. Wiring harness to hitch<---------------->N/A

2. Plug to module<---------------->N/A

3. Brown -- ground (the 7 pin harness only has 1, not 2 as per the diagram)<---------------->Connect to left side of battery ***8220;frame***8221;

4. Black/Red -- Brake Light<---------------->Right tail light harness Black/Blue wire

5. Orange -- switched power<---------------->Green/Red under the glove box

6. cable housing<---------------->N/A

7. Orange/green -- (Turn signal not sure which)<---------------->Orange/Green under glove box

8. Green ***8211; other turn signal<---------------->Green under glove box

9. Cable housing<---------------->N/A

10a. Red/Blue -- connects to 11a which connects to + terminal on middle of battery

If I didn't mention it it doesn't exist on the 7 pin wiring harness.

Ok, now that you have a general understanding of the harness, it***8217;s time to install it. It***8217;s really not that hard once it***8217;s explained in words and not hieroglyphics. Don***8217;t forget to unplug the negative side of the battery. You***8217;ll also need to remove the rear seats. If you have fold down seats lucky you.

I don***8217;t so here are the instructions for removing the seats. First remove the bottom seat section. To do so just grab the cushion firmly in the center of the left or right seat and pull up firmly. You***8217;ll feel it pop. Do the same thing on the other side.

Now the back seat cushion. First remove the two very large torx screws in the middle (T50 in my case). Now you have to crawl into the trunk and throw the two latches with a flat head screwdriver. This is really hard to describe but there is a good youtbue video of course.

youtube video

Now we***8217;re ready to install. Put on the Velcro strips on the BMW module and then plug in the harness to the module and mount it by the battery on one of the walls of the battery well.

Next take cable 3 (brown), undo the bolt holding the battery frame, slide the cable connecter over the bolt and reinstall the bolt. This will be the ground. The instructions show to connect this ground to the left of the battery well, and there is in fact a ground connected there, but the bolt is much to big for this cable connector so this was my alternative.



I've also circled the red power cable that you will install in just a bit at the very end.

Second, take the black/red wire from the harness and run it up the rear right light harness and connect it to the black/blue wire from the tail light wiring using the quick splice connecter provided. Cut off the extra wiring. This is the brake light.



Now uncoil the orange wire and uncoil the harness (6 on the diagram) holding the green and the green/orange wires. Straighten them out as much as possible and try to keep them straight. Follow the wire bundle leading towards the front from the battery well on the right side. You can see in the picture above where I circled the orange wire and the green & green/orange cable bundle (you can't really see the green cables) and how I've tucked them in and followed this massive cable bundle.

You can slip the cables through some the mounting straps as you do so. When you get to the rear seats you can slip them into a protective plastic tube that then feeds them into the plastic trim running down the side of the interior of the car. I was able to slip the cables behind the plastic trim with my fingers without removing the trim. I think I only used 2-3 of the plastic zip ties in this process. I believe those cars with PDC stop at the rear seats, lucky them.

Once you***8217;ve gotten the wires up to the front you***8217;ll need to remove the panel under the glove box (two T25 torx, unplug the power outlet and the light), and also the glove box. The instructions don***8217;t say to remove the glove box but it will make your life so much easier if you do. Remove 4 T25 torx at the top, 2 on the side, and 2 more on the bottom. You will also need to remove the cup holders. To do so remove the panel trim surrounding the cup holder. Just pry it off gently. Undo the four Phillips screws and pull the cup holders out. Don***8217;t put them back in upside down, although that***8217;s hard to do. Now the glove box should pull out and you can undo the connecting cables for the USB, the lights, and the trunk latch.

You***8217;ll notice two large wire bundles up front at the bottom of the glove box. On the one on the right you***8217;ll need to find a set of green and orange/green wires. They will be twisted around each other. You***8217;ll also notice about 3-4 sets of them. Just pick one. You***8217;re going to have a hard time untwisting the set and making room for the connectors but it will go. It helps to undo some of the cloth electrical tape BMW uses. Do one at a time. Here***8217;s a pic where I've circled the two wire bundles you are looking for as well as the orange wire connection for the switched power.



Here's a pic of the turn signal connectors, although you can't really see both of them as they are very snugly together.



Personally I would recommend stopping here and doing a quick check. Reconnect the negative side of the battery and turn on your car. Make sure everything is working before moving on.

I found the wrong cable on the right side bundle and connected the orange cable there by mistake. It sent my whole car into a frenzy. Windshield wipers turned on but wouldn***8217;t turn off, hazards going crazy, dash lights not working, no nav, and who knows what else. To say I freaked out is an understatement. I unplugged everything and started over. Yes the car fully recovered so don't be too panicked. If you***8217;ve done everything correctly until this step there should be nothing bad that could happen and connecting the battery and disconnecting it again is straightforward and easy.

So once you***8217;ve done that check, move on. On the left side bundle find the green/red wire in the bundle and connect it to the orange wire coming from the westfalia brain with the connector. You may want to do one more quick check and connect the battery again and turn on the car. If your car is going to have a fit it would do so now. If it hasn***8217;t, well congrats you are basically done. Just one more cable to connect. I still wouldn***8217;t start putting the car back together until you actually have everything connected and can test to be sure everything works as planned.

Go back to the rear of the car and connect cable 10a (red/blue) to the fuse connector (part 23, only 1, see pic above). You will slide in the tip from cable 10a and also the tip from cable 11a into the plastic junction box first. Snap in the clamps. Now you can plug the 20amp fuse into the top. Once that***8217;s properly built look on the left side of the battery towards the middle. You will see a large red cable under a plastic cover. Flip open the cover and you***8217;ll see it is held in by a nut. Undo the nut (12mm I think), slide off the cable, slide on the connector from cable 11a and then slide on the connector for the other red cable and redo the nut. That***8217;s it, your done. I would now connect the battery again, loosely, turn on the car (not the engine though) and start testing the output to the 7-pin connector on the hitch. Test turn signals, brake light, night lights, etc. If everything is providing power as planned go ahead and put everything back together. It's best to use a simple 12v test light to see if you have it working properly.

This is a long post, and this may seem like it would take a long time based on my description, but in all honesty, if you read this post a few times, watched the videos and visited the other links, you***8217;d probably spend just as much time getting ready for the install as the install itself would take. I know there are much cheaper options but this thing is very sturdy, doesn't stick out at all, and it plays well with my electronics as the thing was made specifically for BMW, plus given that I have a 335d I really had no choice.

Good luck jim
 

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I installed a Westfalia OEM hitch on my 335d (e90) and I figured there might be others interested in doing the same. If you are one of those people who just can***8217;t wrap your head around a BMW sedan towing anything, please move on. I***8217;ve all ready made that decision and know for a fact these cars can tow with out any negative repercussions to the car, its frame, or its engine.
Welcome to Bimmerfest! Very nice and informative first post!

During our European Delivery we saw BMWs towing all kind of trailers and small campers. We even saw a 5 Series towing a double horse trailer!

I have both a German and a UK 3 Series brochure and they both show a trailer hitch as OEM accessories. Not sure whether it's because of state/federal regulations or BMW NA's idea that it might tarnish the brand image that trailer hitches aren't more readily available for 3 and 5 Series in the U.S.

I agree with Salvator, where's the pictures of the completed project?
 

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Discussion Starter · #4 · (Edited)
Coming soon! I'll post as soon as I get the tow bar back from the welder and I have to remount the bumper. I was hitting the DEF tanks with the tow bar but I did some measuring and it's an easy fix for the welder (another $50). I'm gone for a week of vacation but when I get back it should be ready to install. I'll take a pic then of the final product and look. Yes I have to take of the bumper skin again. I left off all the mounting screws and trim screws for now so it should only take me about 20-30 minutes to reinstall.

Not my first post, just my first DIY post in the E90 forum. Did a few DIY's over in the E46 side of the forum as well.
 

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Not my first post, just my first DIY post in the E90 forum. Did a few DIY's over in the E46 side of the forum as well.
My bad. I could have sworn that when i went back to look at your first post in this thread that it said 1 post. Obviously not.
 

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Discussion Starter · #6 ·
335d hitch install follow up

Finally got my hitch back from the welder and found some time to finish the project and take pictures. He did a really good job meeting the specs that I gave him and he did a beefy job with the welds and repositioning of the hitch attachment due to the DEF tanks on the 335d.

Here is a picture of the towbar after the welder was done. He centered the hitch and also shortened it (from front to back) and kept the ball at the same height as before. The problem was the DEF tanks on the USA 335d. As you can see here the hitch is still coming REAL close to those def tanks. But I can tell you they are actually NOT pressing against them. The right circle shows you where the electrical connections are held.



In this pic the tow hitch parts are circled in red. You can see better where the electrics will hang and also the housing unit for the tow bar. In blue are all of the bumper skin mounting points.



Here's the back of the car and the electrics are tucked away (they rotate and lock in place, up or down, depending if you need them). You can BARELY see the bottom end of the hitch. Once I removed the sticker you don't notice it is there.


And a closer look with the electrics hanging down.


A view from underneath. You can see the electrics tucked away under the bumper.


And one with the hitch on and the electrics hanging down.



I am VERY pleased with this set up and very glad I did it. If you are contemplating this let me know and I can give you the specific instructions that you need to tell your welder. It really isn't that complicated.
 

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Discussion Starter · #8 · (Edited)
For the wiring I first installed this adapter at the ends of the wiring coming from the "brain" part (Hopkins HM48915 $15). This takes the brake light and merges it with the right and left turn signals. The problem is this.
The Euro 7 pin 12n adapters wiring is:
1. Left hand turn signal
2. Fog lights
3. Ground
4. Right hand turn signal
5. Right hand tail lights
6. Brake light
7. Left hand tail lights

The USA wiring is
White - Ground
Green - Right hand turn signal and stop
Yellow - Left hand turn signal and stop
Black - Running lights

So I ignored the fog light, just cut and cap it, and then I connected only one of the tail lights, cut and cap the other one. So that merges 5 wires down to four, if you are counting the ground.

Then I took that adapter and connected it to this round adapter which I mounted to the round westfalia mounting bracket. (Hidden Hitch 4 pole knockout adapter $5). Pretty smooth.

eurohitch.com sells an adapter to go straight from the 7 pole 12N euro connector to a 4 pole USA but it's $70!!! Again their prices are insane, which is one of the main reasons I chose to do it myself and find my own work arounds.
 

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Thanks. I didn't care for that $70 plug either. Thought I would make my own using one of the other adapters and a 12n plug. Your solution is much cleaner and far less costly. If I'm reading it correctly you are not even using the euro socket that comes with the kit but instead using the two adapters.

Did you do anything for the safety chains? I'm thinking a couple of 'U' bolts welded to both sides of the flats that hold the vertical receiver. Hitch due here next week so I'm not sure on the clearance for the bolts.
 

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Discussion Starter · #10 ·
yeah I just left out the euro plug as it just confuses thing. It would have been nice if someone made a 7 flat blade adapter that takes into account the separate wiring in most euro cars but that was too much to ask. Then you could have just plugged in the wires to the correct connection and used a 7 blade to 4 pole adapter. Would have been cleaner but this works. Just zip tie the new module to the bumper with the other wiring to keep it out of the way and protected.

The tow bar has a beefy loop on it, I assume for the chains. Hard to see in the pictures above but you can sort of see it in one of the pictures.
 

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Discussion Starter · #12 ·
This is a round mounting bracket. It also faces down and has a very unique mounting point. You should take a look at pfjones website and look up the towbar listed above. They have some video and pictures with better pictures. I doubt you could find anything that would work with the westfalia setup in the US to do a bike rack. You might be able to order one from pfjones but I wouldn't know. I have a bike rack that I put on top of the car.
 

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Discussion Starter · #13 ·
Update on this project. I did get that $5 adapter plug installed very smoothly inside the westfalia plastic housing. I'll take some pics and post later. I was surprised how easy of an install it was. It does take buying a $1 piece of pvc pipe and cutting it and some super glue but I had both of those lying around the garage.

Unfortunately that $15 hopkins 5 wire to 4 wire (they actually call it a 3 wire to 2 wire adapter) adapter does NOT work. Haven't figured out why yet. The taillights work but the brake and turn signals do not. I will tell you that I had an old Hopkins #46255 converter lying around and I plugged that into the wiring and that converter does work. The big difference is that it connects directly to the battery. I don't know why or if that is important but it is a major difference between the two. I have contacted the guys at etrailer because I want a solution that doesn't require me running a cable back inside the car and I'm hoping there is a solution. They did mention the brite-lite adapter might work but that's $45 and not the cleanest fix.

Realistically I might just install the old adapter I have but that means taking apart my bumper skin again!!!! Mostly it's just annoying taking off all those bolts. If I hear something from etrailer with a different solution I'll let you know. I think a new Hopkins 46255 is around $40. Personally I would just order that now and install it before you put your bumper skin back on.
 

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Little late... Will see if etrailer accepts returns. If we're using that Wiring Harness than there isn't any real reason to get the euro wiring kit.

If you don't want to take off the skin. Use the fog wire as your power source. That way when you turn on the fog lights your turning on the trailer lights.

Is the 4pin plug molded into to brains or is it a pigtail?
As we need a powered converter than HM48895 should also work at half the cost.

I would like to see that mounted since I'm already getting the housing
 

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Another thought. The switched power orange wire (which I assume is fog light) make that into a fused connection to the battery. That would than provide all the needed wiring for the powered converter from the euro harness.

Now if that switched power isn't the fog but something fancy for the brains, than cut the fog wire from the brains to the socket and make that the fused connection to the battery.

I'm thinking of doing the latter since you're not really making any change to the euro kit. Removes guessing if the orange wire is for fog or brains as it will still be wired to the brain.
 

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Nice job! Thank you. Excellent that it's so stealthy when not in use.
 

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Discussion Starter · #17 ·
I talked to the people at e-trailer and of course they really didn't know much beyond "well this works here and this works there" but not being able to explain how or why it worked. Long story short I kept the BMW module and then connected the Hopkins #46255 converter behind it in the battery well. Then I rain a pig tail from inside the well along the bumper and down to the Hidden Hitch 4 pole knockout adapter $5 that I had installed. I kept the BMW module because it tells the computer that I am towing and also if there are any issues with trailer lights it will tell me. If I was starting this over I would just NOT order the BMW module and just install one of the other powered modules. Should save you some money. Or if you must have the BMW module to talk to your cars computer I would just bite the bullet and buy the $75 adapter from eurohitch.com

Here's some pics of how it looks. The bmw and the hopkins modules are all in the battery well but I didn't get a picture of that.





 

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Discussion Starter · #18 ·
Update to towing system install

Another quick update. I found a much better solution to the wiring for the power connection to the battery while upgrading my sound system and adding a DSP and new speakers. Wish I had seen this earlier. You'll need to order part #61136920094 ($1.50). This is a metal terminal that you can slide into the battery. You should have a couple of free spots open. You may also need to order the plastic housing.
Universal socket housing MAK8, uncoded 2 POL. 61136925166
Universal socket housing MAK8, uncoded 1 POL. 61136925176
Depends on how much free space is on your battery. Take a look at these pictures:





These are not my pictures but I found them over on e90post.com and thought I could highlight them here.

It will be fairly obvious where the plug goes when you unplug one of those plastic connectors. Look for ones that have a spot for two connections but only one is being used and that is where you slide the new terminal. Of course make sure the negative on your battery is disconnected.

I'm still using the two towing modules in series and it's working great. One of my wires on the trailer became disconnected and the vehicle's warning lights let me know exactly on which side the problem was.

And here's a pic of me towing:

 
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