DIY PDC -Parking Distance Control- Reverse Sensor

[muddtt]

Looking out the back of a 135i vert with the top up left me with an extremely limited view of things. Decided to install an aftermarket PDC system for safety. I like the idea of audio only reverse systems because IMO you should be looking backwards while reversing. That and adding a camera will force me to add another screen to the dash and add clutter. Anyways here's my install. I just added the major points that aren't in the instructions given with the kit.

The kit I purchased was:
IMG_0179 by jsk945, on Flickr
This can be found on Amazon or search Google for the model number. It is very similar to a Steelmate kit I've used in the past which was very good quality. I say it's better quality than most ebay kits because it has quick disconnects sensors for the bumper. Most of the cheaper kits just have long sensor wires that just go straight to the electronics box. This would be bad in the event of any scenario where the bumper needs to be removed or replaced.

The fact that it came in gloss black to match my bumper was just a bonus. I figured it would come matte black and I would just have to paint them.


1) Oh, before I forget...It might be a good idea to unplug the trunk light just to save battery. It'll be open for a long time. It is simple to pry the light off by hand and just pull out the plug.
IMG_0166 by jsk945, on Flickr

2) The first thing I did was to crimp some plugs on to the end of the wires from the power wires that power up the kit to test it. These are plugged into the wiring harness for the reverse lights. The reverse lights are really easy to access. I worked using the passenger side. Just open the trunk and pull off the felt cover in the trunk that allows you access to the reverse light bulb assembly. Just push the tab and pull out the harness. Mine slid out easily.
IMG_0165 by jsk945, on Flickr

The slots/wires that eventually need to be used are 5 and 2. Number 5 is the positive and number 2 is the ground. Or in wire color, The mostly brown wire is the positive and the mostly black with purple stripe is ground. (another picture of this to come later when spliced in).
IMG_0167 by jsk945, on Flickr
Just plug the spliced wires in, make sure it's attached to the electronics box, and plug in the speaker. Once this is done throw the car into reverse with your foot on the brake and listen for the startup "BEEP" sound to make sure your box powers up correctly. For those that are a little slower, the kit is powered up along with the reverse lights because the only time you want the unit on is when the white reverse lights are on. So it's a convenient place to splice power from. With all that tested and working properly it's time to get to the scary part...drilling the holes!

3) Get under the car and remove the little valence thingy to give you more access to underneath the bumper. This mod doesn't require you to remove the entire bumper cover, although you could if you have lots of time. There should be 6- 8mm bolts underneath and then the rest of the valence just pulls straight out. I included a picture of the tabs that hold the valence on so you can get an idea. There's another lower body cover in the center that can be easily removed to allow arm access straight up the center of the bumper. It just requires 2- 10mm bolts to be removed.
IMG_0169 by jsk945, on Flickr
IMG_0168 by jsk945, on Flickr

4) Put some painters tape across the length of the bumper. I used some string with a weight as a plumb line to get the center position on the bumper. Mark that with your favorite color marker.
IMG_0170 by jsk945, on Flickr

5) For the position of the sensors I just used recommendations in the instruction manual and compared that with pictures of OEM PDC bumpers. The first holes were 9" from center. The second set of holes were another 15" from the first set of holes. Mark those distances with your trusty marker. For the height of the sensor holes, I measured down 1" from the curved edge of the bumper. Just hold up the sensor to get an idea of what it'll look like and where you want the sensor position to be on your bumper. Again, it looked about right compared to OEM bumper pics. Picture isn't that great, but you get the idea.
IMG_0171 by jsk945, on Flickr

6) Time to drill some holes! Suggestion: measure three times taking a break in between one of those checks to clear your head. Then have a friend check to make sure you are putting the holes in the right place. Once the holes are in there there is no turning back! Another thing I did was to reach my hand up and behind the bumper cover to make sure there was nothing to interfere with the drilled hole location. Just for your assurance there is plenty of room in the locations that I used for you to be way off and still have no interference. The instructions say to use some sort of pointy object to gently hammer in some start up points so your drill doesn't wander. I did that and used a 1/16" drill bit to make starter holes. Then used the hole saw drill bit included with the kit. TAKE A DEEP BREATH...then start drilling.
IMG_0172 by jsk945, on Flickr

7) Now that your holes are drilled, remove the painters tape. I used a sharp knife to deburr the outside of the holes so the sensors sit more flush. If you butcher the deburring a little its no big deal cause the sensors will totally cover the holes. Go ahead and push in the sensors now. Make sure you got the sensors oriented correctly. I think mine said 6 degrees on the tops of the sensor. Just look at the pictures in the instruction manual. From here I connected the longer wires. These are labeled A, B, C, D. In the end, these designations don't really matter, but just so you feel like you're doing things right put them in the right order.
IMG_0173 by jsk945, on Flickr

8) Run the wires to one side of the car. I chose to put my electronics box on the passenger side so I ran all of my wires in that direction. If you look on the inside of the bumper with a flashlight you can see that there are actually 2 sets up clips to run wires along. The first set kind of looks like a K and the second is beefier and right on the bumper. Hopefully you have skinny fingers and arms for this part. I used some zip ties to hold the wires on these hangers so they wouldn't fall off. The reality of this step is just keep the wires away from the exhaust so they don't melt and secure them so they don't bang around and make noise. If you accomplish that you're good to go with this step.

9) Remove the passenger side brake light housing. First remove both wiring harnesses. There was the one that we removed to test the unit and there is a second one higher up. Next, I removed some of the clips that hold on the trunk felt material around the brake light area. This was done so I could pull back the material and gain access to the 3 nuts that hold the brake light housing on. Think these were 8mm nuts. Unscrew them and the housing should pull off easily. Caution: Don't drop the nuts
IMG_0180 by jsk945, on Flickr

10) I then plugged all my wires into the electronics box and put the cover on. I tucked the fuse into the box as well. The box location is the step that gave me the most pause. I couldn't find an easy place to allow me access to the trunk for a safe place to put the box. I mounted my box on the metal part using the double sided tape in the location of the picture below. It looked clean and a place where not much water goes??? This might be where the complete removal of the bumper cover or the wheel well would have exposed better mounting locations for the box. I just wrapped my box with some electrical tape for the event that a little water might trickle down there. In the worst case scenario a fuse might blow or sensors stop working and I'll shell out another $60 bucks and find a better place to mount the box.
ECU loc by jsk945, on Flickr

11) I ran my red and black power wires into the trunk through the larger reverse light hole. I ran the Beeper wire through the smaller hole higher up. I figured the foam was enough to seal even with the wires there.
wires by jsk945, on Flickr

12) Remove some of the tape that holds the wiring harness wires bundled. Crimp the power wires to the appropriate wires in the picture using the supplied splicers. The first time I did this the metal in the splicers didn't completely come down on the wires and I didn't get power to the unit. I used pliers to press down the metal more and cut through the wires better. You'll understand when you see the included wire splicers.
IMG_0174 by jsk945, on Flickr

13) I mounted my beeper in the nice cut out hole that was already provided in the trunk. This is another area where you might find a better location for the beeper. I can clearly hear the beeper in the trunk with it closed, but a better location would make it more audible.
IMG_0176 by jsk945, on Flickr

14) Time to test. If you have a friend for this it would make things safer. Turn on the car, pull the parking break all the way up, put blocks under the wheels to make sure the car doesn't roll anywhere. (Just be smart about this step). Put your foot on the brake and car in reverse. You should hear an initial beep to tell you that your system has turned on. You can leave the trunk open at this point to hear the beeper better. Next, carefully take your foot off the brake and if it isn't moving get out of the car and test the sensors to make sure they read distance correctly. If you have a friend this would be even better. Just use a magazine or something so that you can work with one sensor at a time and make sure they are reading distance correctly. If everything works put the car in park and shut if off.

15) Tidy up your wires and put everything back together. You're done!
IMG_0177 by jsk945, on Flickr

Haters are going to hate and say they look ugly. To be honest I've never thought twice about reverse sensors on any car except on some American SUV's where they bring ungodly attention to them. Damn that took 2 hours to write up. Hopefully at least 1 person can make good use of this.

[New21er]

Nice job and great write up! Thanks

[suspenceful]

Although I have factory PDC sensors, this is a great write-up!

I don't think they look bad at all...

[champignon]

Great write up, thank you!

So, almost a year and a half later, how is this this working out? Any issues with the product, your install, or vehicle electrical problems coming from the installation?

Any things you would do differently now?

Thanks!

[muddtt]

Originally Posted by champignon

Great write up, thank you!

So, almost a year and a half later, how is this this working out? Any issues with the product, your install, or vehicle electrical problems coming from the installation?

Any things you would do differently now?

Thanks!

Things are still working perfectly. If I could I would try to find a way to run the speaker wire thru the trunk into the cabin... the beeper is a little bit quiet with the top down, but not a deal breaker. Still works fine as long as your listening for it. Plus with the top down its not really hard to reverse :P

[champignon]

Originally Posted by muddtt

Things are still working perfectly. If I could I would try to find a way to run the speaker wire thru the trunk into the cabin... the beeper is a little bit quiet with the top down, but not a deal breaker. Still works fine as long as your listening for it. Plus with the top down its not really hard to reverse :P

Thank you!

[Matticus91]

I am one of those people who isn't a fan of the way they look but I live in the city and parallel park often, so this might just be a good move.

How well do you find them to work in the real world? Do they pick up only solid objects or if you were backing up to a wire fence would it catch it?

Great write-up I'm sure a few people at least will find it useful, me included!

[muddtt]

Originally Posted by Matticus91

I am one of those people who isn't a fan of the way they look but I live in the city and parallel park often, so this might just be a good move.

How well do you find them to work in the real world? Do they pick up only solid objects or if you were backing up to a wire fence would it catch it?

Great write-up I'm sure a few people at least will find it useful, me included!

To be honest, I can't remember the last time I ever had to back up toward a wire fence. It has picked up bushes, curbs, those cement parking blocks.
Overall I've been quite happy with the performance. Especially when parallel parking.

[Matticus91]

Originally Posted by muddtt

To be honest, I can't remember the last time I ever had to back up toward a wire fence. It has picked up bushes, curbs, those cement parking blocks.
Overall I've been quite happy with the performance. Especially when parallel parking.

How high of a curb? That would be helpful as well

[muddtt]

Originally Posted by Matticus91

How high of a curb? That would be helpful as well

dunno...never got out of the car with a tape measure and checked. Just whatever you'd think is typical for a curb or parking block.