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