Remember when all new cars started to get electric windows? There were plenty who sneered at them - why would you need those? they asked. Same with cruise control, same with interior light delays - you name it, those that didn't have it hated it. Of course, once they experienced the usefulness of the device, all that derision suddenly changed...
That's much the same with reversing proximity sensors - you know, the things that go beep, beep when you're about to back into something. Nah, why'd you need one of those? Can't you drive, buddy? Thing is, once you've experienced the usefulness of the device, you tend to think the opposite - why not have one? Plenty of cars these days have reversing sensors as standard equipment - even the BA Ford Fairmont has such an option.
Well now you can buy a very effective, low-cost reversing proximity system - and fitting it is dead easy. The Parking Sensor kit is available from Jaycar Electronics stores. It costs just under AUD$100.
What You Get in the Box
Inside the box you'll find two sensors, a buzzer, a control box, a power cable and some double-sided sticky Velcro.
In more detail, the control box plugs into the two sensors and the buzzer. It's powered directly by the reversing lights, saving you having to find a power source elsewhere in the cabin. If this box is mounted close to the reversing lights, then it all becomes very easy...
The supplied beeper is quite loud - and it needs to be since it will be living in the boot and so the sound has to travel a fair way to get to the driver's ears. It pulses at different speeds and frequencies, depending on how close you are to the obstacle.
The two sensors are weatherproof and come with double-sided adhesive tape already attached to their backs. If required, additional screws can be used to hold them in place.
Fitting the Sensors
The first step is to work out where the sensors will go. The sensors needed to be mounted symmetrically around the centreline of the car, 100cm (plus/minus 10cm) from the ground.
Since power comes from the reversing lights - and since it makes sense to keep the sensors, control box and buzzer together - the next step is to switch on the reversing lights to find out where they are. Here they're actually mounted on the bootlid. That made putting the sensors either side of the numberplate a pretty good idea, although where possible they should be spread further apart than this.
Lifting the bootlid showed a removable trim panel running under the lip of the boot - perfect for hiding the cables going to the sensors.
To get full access the bootlid trim cover was removed...
...and then the tail light mounting nuts undone and the tail light popped out a bit from its normal mounting position.
The cable going to the sensor could then be fed through a revealed hole before the trim and taillight were returned to their normal positions. The same process was then completed on the other side of the car.
Inside the bootlid a grommet was placed in a convenient existing hole, and the sensor cable passed through it.
Back on the outside of the bootlid, the paintwork where the sensor would sit was cleaned...
...and then the sensor was stuck into place, using the provided double-sided tape. The same was then done for the other sensor.
Fitting the Buzzer & Control Box
The buzzer was tried for size in a recess in the bootlid and then stuck in place there using the Velcro double-sided adhesive tape. While it is loud, if your car has a lot of soundproofing you might like to mount it closer to the cabin. There's plenty of cable to let you do that.
It's not worth cutting the cables and then rejoining them - after each cable was plugged into the control unit, the excess was bundled up and cable-tied before being tucked away.
The control unit was then stuck into place inside another convenient recess. Note that the main power feed is yet to be connected - this cable is still hanging free.
On the right is the power wire to the control unit and on the left are the power and earth feeds to the reversing light.
With the reversing lights on, a multimeter was then used to (a) confirm that these were in fact the right wires, and (b) which was positive and which was negative.
The wiring connections were then soldered and the joins wrapped in insulating tape.
The interior bootlid trim could then be replaced and the installation job was finished. Yep, that easy.
The sensors are only just visible beneath the trailing edge of the boot, however their angle of view is still substantially unobstructed. This position also gives them added protection against the weather.
Does it Work?
The system has five levels of alert - between 1.5 - 1.8 metres it slowly beeps, from 0.8 - 1.5 metres it fast beeps, 0.4 - 0.7 metres it's at its fastest, and then at less than 0.3 metres it is on continuously. In this installation, where the bumper - not to mention the towbar - is much closer to the obstacle than the sensors, you don't ever want to hear the continuous beep!
In this installation the Lexus soundproofing is excellent and so the beeper can only just be heard - it would have been better to attach it to the back of the seat or up under the rear deck.
The device isn't infallible - with these sensor locations, a single post positioned directly behind the outside edge of the car won't be picked up. And if the object that you're backing towards isn't solid - eg it's a bush - or has different levels placed at different distances from the car, the system can become a little confused. However, it works very well when you are reversing towards a wall or another car - so it's perfect when you have to get out of a tight ranking or you're in a multi-storey carpark and you want to reverse as far in as possible...
www.jaycar.com.au
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