HOW TO - Fit aftermarket parking sensors (rear) with display

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R2e

Active Member
Joined
Apr 3, 2007
Messages
330
Location
Tunbridge Wells
Car
ML320 W163 with LPG
I’ve just fitted a set of aftermarket rear parking sensors + display to my W203, a good Easter project, and thought my trial and error experiences might be useful for others. Unfortunately, I didn’t think of taking pictures while actually doing the work…….

1. Fitting the sensors
I used these sensors - http://abarnard.ecs2.co.uk/4004-reversing-sensors-with-digital-display.asp - which I colour matched as per the website instructions with spray paint from Paints4u, 2 thin coats of colour, one of clear.
Firstly remove the rear bumper strip which is held on with clips. It is necessary to remove the outer strips (which go round the corner to the wheel arch) first. Note that the end nearest the wheel arch is held on with a screw inside the arch lining, if you don’t remove this the little bracket breaks (don’t ask how I know this…!) though as the clips seem strong this is not a problem and the strip holds fine. Check the gaps between centre piece and corners as you need to recreate the same gap later, when fitting or you end up with the centre bit too much to one side and have to do it again (don’t ask how I know this either….!). Preferably use something plastic to lever off the strip to avoid damage. Incidentally, any scratches can be touched in by spraying a little of the paint mentioned above into the aerosol cap and applying with a small brush.
The centre strip has four circles (very faint) marked in the plastic to show where the sensors should be fitted. I found the centre of the circles by making a circle the same size with a pair of compasses, cutting out then holding in the circle on the plastic and marking the centre with an awl. I used a small drill to drill through from the inside, then used the hole cutter supplied in the kit from the outside. I cleaned up the hole with a knife (the plastic tends to melt slightly and stick) then fitted the sensors.
The bumper itself already has the holes for the sensors, though the outer ones have a strip of plastic across the centre of the hole which needs to be cut off with a sharp knife.
Feed the sensor wires along inside the bumper right to left.
Now remove the internal trim from the boot. There are round and oblong plastic clips holding this on, all work on the same principle and the centre part should be removed, then the clip itself. The rear part around the lock should be removed first then the nearside trim which covers the lamp and rear SAM.
Below the rear lamp is a large rubber bung which, when removed, leaves a hole which lines up with the nearside sensor, the sensor wires should be fed through this hole. It is possible to obtain a grommet for this hole, but I simply cut a cross in the middle of the rubber bung and pushed the wire connectors through. A dab of silicone will seal this up later.
Refit the centre strip while pulling on the sensor cables to tighten them up and avoid them being trapped. It is a good idea to fit one of the corner bits first and ensuring the gap is correct when fitting the centre

2. Fitting the control box
I decided to use a relay on the reverse light to avoid CANBUS or bulb sensor problems, this may or not be necessary. The relay and the control box were stuck with double sided tape to the rear SAM (which was detached to make things easier). The relay was provided with a feed from a suitable ignition switched power source, reverse sensing from the wire leading to the reverse light, earth and connection to the control box. The control box was also earthed and all the sensors attached. All wiring was done using ‘piggyback’ connectors, not elegant but functional, and they can be removed at a later stage. At this stage the system was tested by connecting the display unit, putting the car in reverse and approaching the rear from all angles while watching the display.

3. Fitting the Display unit
This is the tricky bit. The wire from the Display unit has to pass from the front of the car through to the boot. After much experimentation, the following was found to be the easiest method.
a) The console trim was removed, as was the radio. (This is covered elsewhere so I won’t repeat here). The speaker cover on top of the dash was removed (This simply levers out, but use something plastic to avoid damaging the dash.
b) The cover under the glove box was removed (two screws just below the front of the glovebox) and allowed to hang down.
c) The left footwell trim was removed. This is held on with a central screw hidden by a small cover, and two clips under the weatherstrip. It is necessary to pull the weatherstrip off to access and lever off these clips.
d) The front and rear door carpet trims were removed, these pull off, though the rear one is also clipped at its front end so pull up to remove then pull back to slide off the front clip. Below these is a plastic conduit where the existing wires run through to the rear, etc.
e) The rear seat squab is pulled up on the nearside to allow access to the bolt which holds the bottom of the rear seat back. When this is pulled back the wiring through to the boot can be seen.
f) From inside the boot, just above the wheel arch on the nearside, a large piece of foam is removed to allow access between the boot and the interior of the car.
g) The Display Unit was positioned on the top of the speaker cover and a small cut made on the NSF to allow the wire to pass through. The Display Unit wire is then fed over the speaker bracket and down the front of the console into the place where the ashtray fits. It is then possible to feed the wire through into the passenger footwell.
h) At this stage the Display Unit can be glued to the speaker cover using the supplied double sided tape and the speaker cover, radio and console trim refitted.
i) The wire is taken along below the glove box and down the side panel into the conduit under the door carpet trims, through to the back of the car and up and over the wheel well into the boot and connected to the Control Unit.

And that’s it in a nutshell. Obviously take care to route the wires where they will not be damaged, or get in the way of anything else, Tape wires together and tape to existing cable runs for neatness, and put everything back the way it was. A wedge shaped piece of plastic is the best thing to use for levering the various bits off, I used one that came with a Brodit mobile phone/pda holder kit.


I’m delighted with the result, particularly as the Display Unit matches the light grey dash on my car and looks as if it could have been an original fitment. I think the sensors look good too and match the paintwork very well.

The pics show the rear strip complete with sensors, and the display showing an obstruction to the right rear half a metre away.
 

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Many thanks for that - I will seriously consider doing it to my car - how long did it take you? I'll just double the time...lol:rock:
 
Nice work dude. Looking good :bannana:
 
Brilliant! MB club members at their best!! ...posting nuggets of gold like this! BIG THANKS for the info and the link! You'll save thousands of pounds in crunches and repsprays for other forum members :)
 
How long did it take? I hate to say.............!!

However - removing the rear bumper strips is a matter of minutes once you get up the courage, I would guestimate 30 - 60 minutes at most for the job, assuming the sensors are sprayed in advance.

Fitting the display unit was a different kettle of fish, but that was due to taking various blind alleys trying to get the wire through to the rear. With the knowledge I have outlined I would guess no more than an hour or two for this bit.

Final wiring, depends on your level of knowledge, but actually is fairly simple. I identified around the area of the rear SAM (with the test screwdriver provided in the kit - they think of everything!) the reverse feed, a 12v Ignition feed and the earth (brown) and using the piggyback connectors (blue, from Halfords, box of 10 I think. The connector fits over the wire you're tapping into, the new connection pushes in, then you squeeze the metal bit with a pair of pliers and clip the plastic clip over), probably no more than 15 minutes for this. Add in 15 minutes to remove the boot trim and you have a total of 2 to 4 hours in total. Now I've had it in operation for a day or so I'm very happy with it.

Ron
 
i fitted my display on the rear pacel shelf, so you can see the display in the rear view mirror when looking at where you are going, also it is a lot less hassle comparing to mounting on dashboard,
 
Is it possible to fit front ones too...and run them off the same display? Or is that too ambitious??
 
Is it possible to fit front ones too...and run them off the same display? Or is that too ambitious??

Unfortunately the front and rear set comes with a different, LCD, Display, and the control unit for the rear one only takes four sensors. I guess it wouldn't be beyond the realms of possibility to set up some sort of switchover for the display and use the same set, or at least the same control box, on the front. Hmmmm, got me thinking now.........;)
 
Unfortunately the front and rear set comes with a different, LCD, Display, and the control unit for the rear one only takes four sensors.

I don't know if it is of any interest, but FWIW, this setup sounds similar as my factory fitted Parktronic (both on my current car as on my previous W140):

6 sensors on the front, 4 sensors on the rear;
Range of the front sensors is 15-60 cm for the corner ones, and 20-100 cm for the centre ones;
On the rear the range is 15-80cm for the corner ones and 20-120cm for the centre ones.

So, the first yellow segments will light up at the indicated maximum distance, with more segments added as you approach the minimum distance, where all segments are lit and the continuous tone is heard.

In the front, the area covered has a wider angle than in the rear.

As for the display units, there are 4 of them, 2 on the front dash (in the centre covering the left hand side of the vehicle and right of the steering wheel for the right hand side sensors). In the back, the 2 displays (left and right hand side of the vehicle) are mounted on a console above the rear window, so they are visible in the rear view mirror.
 
Is it possible to fit front ones too...and run them off the same display? Or is that too ambitious??


If you can source the front sensors separately then a change-over relay driven by the reversing lights will decide which signal (front or rear) to feed to the controller. Easy :rolleyes:
 
When you switch gears into reverse is there a beep to show the system is on? Or does it only beep when it detects incoming surroundings. My wife has it and it's incredibily annoying when she goes into reverse and it beeps for two seconds even when there is nothing close.

LK
 
When you switch gears into reverse is there a beep to show the system is on?

On my factory fitted system, there is no beep when switching into reverse, except of course if something is within the nearest range of the sensors.
 
If you can source the front sensors separately then a change-over relay driven by the reversing lights will decide which signal (front or rear) to feed to the controller. Easy :rolleyes:

Agreed. I'm thinking round splitting the display cable in the dash, making up a pcb with a couple of relays, one to sense reverse and connect the reverse through to the display, and ideally you want to sense moving forward up to the automatic door locking speed, not sure how to pick this up, so it provides power while going forward up to 5mph or whatever.

I'll probably have to drive forward into something before I make the effort though :crazy:
 
When you switch gears into reverse is there a beep to show the system is on? Or does it only beep when it detects incoming surroundings. My wife has it and it's incredibily annoying when she goes into reverse and it beeps for two seconds even when there is nothing close.

LK

Yes there is a beep, indicates the system self testing apparently.
 
Nice post

Excellent detail, inspired me to have a go to.

I opted for a wrieless version hoping to save running the wire from front to back. However, I want to supply the front unit from a reverse switched supply. Any idea where I can gain access to the wire and what colour it is? I am planning to install command in next few weeks too and will do all together so front console will be out.

Thanks again for the inspiration!
 
Excellent detail, inspired me to have a go to.

I opted for a wrieless version hoping to save running the wire from front to back. However, I want to supply the front unit from a reverse switched supply. Any idea where I can gain access to the wire and what colour it is? I am planning to install command in next few weeks too and will do all together so front console will be out.

Thanks again for the inspiration!
Which wire do you want? The reverse wire?

This is becoming increasingly difficult to find in modern vehicles as CANBUS wiring has taken over a lot of conventional wiring however the reverse signal can always be found right at the reverse bulb in the rear lamps, you could trace this wire back to a more convenient place :)
 
Yes, the reverse wire. Is it safe to assume it will be the same colour at the reverse light as at the front of the car? Otherwise, have to dismantle everything to trace it which sort of defeats the object.

I was hoping that there must be something at the gearbox end (mines an auto). Hopefully it will be apparent when I dismantle this lot when fitting the command. Can't beleive the reverse light need canbus? That would be a bit OTT. Surely they still work in the old fashoined way using a switch on gearbox????
 
Yes, the reverse wire. Is it safe to assume it will be the same colour at the reverse light as at the front of the car? Otherwise, have to dismantle everything to trace it which sort of defeats the object.

I was hoping that there must be something at the gearbox end (mines an auto). Hopefully it will be apparent when I dismantle this lot when fitting the command. Can't beleive the reverse light need canbus? That would be a bit OTT. Surely they still work in the old fashoined way using a switch on gearbox????
This depends very much on what car you're talking about really!
 

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