VW T28 reversing sensor housing

The plastic shrouds that hold two of the reversing sensors in the rear bumper on a friends van, had broken. A search to get hold of the right size replacement, had proved fruitless.

An original

It is a VW T28 Transporter from 2008. Based on a T5.

The reversing sensor fits in a 20mm diameter hole in the bumper and the sensor has a 15mm outside diameter with some alignment keys and clips to fit a specific housing.

A 3D printed solution

I've made a 3D printed version of the housing that holds the sensor to fit in to the bumper.

It fits both the sensor and the bumper well. It's tight pushing it in to the bumper.

The production is not perfect but that does not affect it's appearance or ultimate function. The lack of flex in the 3D filament, that I used, means that the inner clips tend to snap off. The sensor fits snugly in to the shroud so as long as one clip is holding this secures it in place. A bit of tape could also be wrapped round the housing, to hold the clips in but that has not proved necessary.

The end result works well, so far.

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3D Printing Method

• Filament: ColorFabb nGen. Used to survive the possible outside temperatures.
• Walls: 2mm thick
• Infill: 30%
• Supports: From the build plate, only where the overhang angle is greater than 80 degrees.

I printed it, outside uppermost. This was to get the best finish on the curved edges of the part of the lip that would be visible when fitted to the van. That required the use of supports for the print.

Download 3D models:
VW T28 Reversing Sensor Housing, STEP and STL (Zip)
Licence attribution - small business exception

My models in the GrabCAD library.

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Discovery 2 parking sensor controls

That didn't last long. I am not keen on the parking sensors coming on automatically whenever I select reverse gear.

By removing a single green/brown wire, the sensors can still be activated by the button on the dash but selecting reverse gear does not activate them.

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How I Did This

The reversing sensor control unit is behind the trim in the rear left hand corner.
It can be easily reached by removing the small grill by the back door catch.

The buzzer is separate connected using a pink and brown wire.  This goes back to the larger beige
connector on the unit.

The smaller black connector on the unit is connected to the sensors on the rear bumper.

The other larger beige connector has the power and connections to the switches.

To disconnect the reverse gear switch remove the Green with brown stripe wire.
Be careful, there is a bright green with yellow stripe which looks similar but is the live feed.

The Green/Brown wire goes to 12V when the gear lever selects reverse gear.

To remove the wire:
1. unplug the larger connector and bring it through the trim panel.
2. Cut the cable tie
3. Carefully prise apart the top part of the casing and fold back the small flap of plastic
4. With a small screwdriver or two pull apart the outer casing of the connector and push the
    white part out one end.  Only one end is open so it is obvious which way it can slide.
    Pushing a screwdriver in the other end while pulling both sides apart is fiddly but easy enough.
5. With the white part out use a tiny watchmakers screwdriver to push the metal catch on the
    socket connected to the Green/Brown wire while gently pulling on that wire.  It will come out
    easily if you have pushed the tiny metal catch far enough in.
6. With the socket out, wrap it in insulation tape making sure that tape will not come off.
    The wire goes live when on so you don't want an accidental short to the chassis in the future.
    I like to double wrap it and secure it back to the other wire so it does not dangle.
7.  Reassemble in reverse of the above.  You'll need a new cable tie to finish the job.


Larger connector wiring:
Side One pins
None
Pink - to buzzer
None
None
Red/Grey
None
None
None

Side two pins
Black - probably ground to the chassis (always has zero resistance and zero volts when tested)
None
Green/Brown - To reverse gear lever switch
None
Grey
None
Brown - to buzzer
Green/Yellow - 12V when ignition on

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