Motorhome advice: How to install reversing sensors

We have a 2016 six-metre Benimar Mileo 201 on a Fiat Ducato, which is fitted with a reversing camera, but the fish-eye lens distorts the edges, making distance judgement difficult.

The solution was to fit parking sensors. I read in a review that the Dolphin kit could be fitted to a six-metre motorhome and took the plunge. I was quoted £250 to fit them if I took the motorhome to Chester, so sought reviews from those who had fitted one themselves and decided to have a go.

I spent £59.99 for Dolphin’s rear sensor kit (which includes an extra £9.99 for an additional visual display unit). I also spent a further £7 for the cable connectors, grommets and cable ties. I used the car kit, but the firm also supplies a kit for larger motorhomes with longer cables for £69.95. It also offers the sensors pre-painted in a wide selection of colours for no extra cost to suit any motorhomes that are not white.

It took me an afternoon exploring a route to get the cable from the engine compartment, through the bulkhead and behind the dashboard to a suitable location for the cab display. As it turned out, the cable was just long enough to meet the control unit in the rear.

To install reversing sensors on a motorhome, you will need:

• Dolphin DPS450 rear sensor kit (£59.99)
• Electric drill
• 21mm hole cutter for the sensors (included in the kit)
• Selection of drill bits (5mm, 10mm, 13mm)
• Screwdriver with T20 star bit
• Pliers þ Torch – I used a head torch to keep my hands free
• Small cable ties
• 2 cable lock connectors 
• One 13mm grommet
• Duct tape.

1 The kit you need to fit this set-up. The hole cutter is supplied with the reversing sensor kit

2 The visual display unit was to be sited in the centre console so the centre cup holder console has to be removed – it’s held by three T20 star screws. Two are found by prising out the covers at the top, and the third is under the mat in the centre aperture. When replacing the console, be sure to line up all of the securing lugs

3 The metal support frame is held by another four screws and can be pulled out when they’re removed

4 The fascia under the heater controls is secured by a single screw under the cup holder. Remove this and it simply pulls away

5 The display unit can now be mounted on the fascia. A small nick is needed in the plastic to allow the cable to pass through

6 The lining of the upper glove compartment is held by four screws and then simply lifts out. You can then thread the cable along, behind the dashboard to below this glovebox. Peering down through the glove box, or up from underneath, you can see the bonnet release cable going through the bulkhead

7 Locate the bonnet release cable in the engine compartment and drill a 13mm hole about one-and-a-half-inches above and to the left. Check that there are no cables or obstructions nearby. I used a 5mm and a 10mm bit before the 13mm bit. Cutting away the insulation is difficult due the lack of access. I pulled bits off with the pliers. Thread the cable through the hole and fit the grommet. This is the most difficult bit due to limited access

8 Thread the cable down the back of the engine until it appears under the ’van. I used a plumber’s bending spring to lead it through, but any stick will be helpful. The cable can then be led to the rear of the ’van along a wiring loom, secured with cable ties

9 Now it’s time for the wiring. The red and black power leads need to be connected to the reversing light. Check the polarity of the wires by putting the ’van in reverse (with the engine off but ignition on). On my vehicle the purple wire was the 12V positive. The cable can be easily connected without cutting any wires by using cable lock connectors (or soldering). The wires are inserted and the metal blade is then squeezed into the connector using a pair of pliers

10 Secure the cables to a wiring loom near the location of the control box

11 If you’re lucky, there are places ready to take the sensors, otherwise you will have to follow the advice given in the sensor kit instruction book to locate four suitable points. Cover the location with duct tape and mark the centre for drilling. Drill the 21mm hole with the hole cutter supplied with the kit

12 There are four sensors labelled A to D. They fit alphabetically from left to right when viewing the ’van from behind. Disconnect the lead from the sensor and fit the sensor in the hole with the two marker dots on the back of the sensor aligned vertically. The sensors are a tight fit, held in place by four rubber strips on the side. Wiggling the sensors was ineffective and I found the most effective way to get them to fit snugly was to bash them with the ball of my thumb. Then reconnect the leads

13 Connect all of the leads to the control box, making sure that you get the sensors in the right order. The power lead and the cable from the display met the control box with only a few inches to spare, so don’t try this if your ’van is over six metres long

14 I put duct tape over the connectors for added protection. The box can be secured to the underside of the ’van by the sticky pad provided with the kit, but I added a couple of screws for good measure

15 Bundle the cables together with cable ties as they approach the control box. The spare cable of various length from the sensors can be zig-zagged and cable tied to a handy wiring loom across the back of the ’van

16 Test the system by getting someone to walk around at the back of the ’van with the engine off but the ignition on. It should give an audible bleep as well as a visual distance indicator on the display.

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