So, as part of my ongoing modifications, I am installing Parking Sensors and a reverse parking camera.

I have already switched the light bulbs to LED in order to reduce the amount of power used by the bulbs and instead to increase the available power to other devices such as the camera or the sensors. However, I have an issue that I am wondering - will it need a relay?

I will be hooking up the parking sensors to the Nearside reverse lamp, and also the nearside brake light (so as I apply the brakes, and if the switch is closed, the parking sensors at the front come on). This I believe should be fine and wont offer too many problems, however, as part of the installation of the camera, I will need to power the camera itself (which will be taking power from the Offside Reverse lamp wire) and I also need to power the reverse mirror LCD at the same time. The question I have, is can I run the power supply from the reverse light of the offside, to power both the camera and the reverse mirror / monitor? or will this cause problems, and as such, do I need to install a relay?

Also, if I replace the LED bulbs with normal bulbs, would this then overload the circuit?

At the end of the day I dont want to have to run a load more wires and play with relays if its not necessary, however, I dont exactly want a bonfire in the boot!

anyone able to offer their thoughts on this one?

Personally, I'd go down the better safe than sorry route!!

Ballache over car-beque

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lol, Cheers Sean, I think your probably right there! although I have the foggiest about setting a relay up and I think it will be a pain in the backside trying to wire it all in!

Well the parking sensors are installed and working fine for now but I think its probably best not to run the risk! I just need to learn how to do what I need to do!

Use a relay, a 4 pin change over universial relay that goes like this.

1 to 2

3 to 4

1 being the "live" from your reserve light and 2 being earth

3 being your dedicated live for your camera and 4 being earth

Whenever reverse is engaged electricity goes from 1 to 2 this will go through the relay energising the coil creating a bridge between 3 and 4

From the above image 85 would be a feed from your reverse light positive into the relay and 86 would be from the relay onto the negative of your reverse.

30 would be your dedicated live for the camera/mirror, with a inline fuse from your battery or some other reliable source going to the relay (30) then a feed from 87 straight to your camera/mirror positive. Finally earthing your camera/mirror negative.

Once reverse is on, a bridge is created in the relay allowing what was a dead circuit to become live, running off it's own power.

It sounds far more complicated than it is

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Sounds alright, Is it a soldering job, or is it just spade heads that can be used? and would a standard speaker wire work?

I suppose the last part of the puzzle would be to buy an inline fuse as well!

oh, and one other thing - how would you go about sealing the unit? you dont really want the contacts and everything on show do you? so can you buy a box for it to sit in, or is there no way to close these things?

Also, would anyone know if the linked wire would be suitable for powering directly from the battery?

http://www.ebay.co.uk/itm/330932262344?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2FVehicle-Parts-Accessories-%2F131090%2Fi.html%3F_sop%3D15%26_from%3DR40%26_nkw%3D330932262344%26_rdc%3D1

as I read somewhere it needs to be 12 gauge wire?

To confirm it would be to power the LCD screen, and the camera. I think the above would probably work?

EDIT: Just come across this http://www.ebay.co.uk/itm/Wire-16-gauge-28-foot-long-green-100-copper-for-repairing-car-electrics-/390840106870?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item5affe2bf76 is this what I would need? run that wire from the battery to the relay and then connect the mirror and camera straight into this?

Yeah James you can solder the wires or just use spades heads, you can buy any kind of generic plastic box that's used by electricians to store connector blocks. Or you can heavily wrap it in electrical insulation tape and tuck it away somewhere (that's what I would do) ensure wires dont touch of course.

The first cable is too small 0.4mm tiny cable, you need about 1mm, a 16 guage will do perfectly 16 guage is around 1.3mm.

In general domestic wiring lights use cable sizes of 1.5mm and sockets use 2.5mm.

1.5mm is over kill for what your doing so 1.3mm will do just fine

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Cheers Kurt, the other thing I guess, is should I be getting special electric cable or would 16 gauge speakers wire work for this job?

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Just off the back of your help Kurt, I have bought the reel of wire as posted just prior to your reply, so should hopefully do the trick!

Any cable will do really the difference is that speaker cables are flexible and shaped round or flat it will be fine either way

One part I don't understand actually is how do you intend on getting your fron side parking sensors working james?

There are timer relays out there that you can use reserve to trigger it then the relay can leave your front parking sensors on for a set time untill reverse is selected again

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Thats all done and working. Basically, the front parking sensors are wired into the brakes. so when the brakes go on, the front sensors come to life, then reverse engages the rear. Works rather well, the only tiny detail is that when reverse parking, I have to creep without brakes until the last moment, as the brakes trigger presidence in the sensors, so the rear switch off and then the front come to life!

on a sidenote, I have also bought a set of inline fuses. I will have the main power from the battery (probably will wire it into the fusebox in an unused fuse port with a wire tap!) then run the wire to the back and the relay, and ground it there. Then run the two wires to the camera and the mirror with an inline fuse in each to keep the risk of blowing it up to a minimum!

Sounds good.

When brakes are pressed how long does the front parking sensors stay on and or how do they go off?

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Just powered for as long as the brakes are depressed. Doesn't affect stopping behind traffic (I bought a 12v remote so I could turn them off incase it did my head in) but it's not an issue.

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Just on a sidenote / question, would you trust amalgamating tape to be the wrap around for the relay?

It has recently become my most favoured of tape products, and if I could use it as cutlery I probably would :p but I think it should offer a good level of heatsoak and security or is that a bad thing in this situation?

Nope that's perfectly fine. It is also insulating so does both

I kind of like the front parking sensors idea for fun james but I keep telling myself that I don't need it lol it just sounds cool

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haha, I do need it, my bonnets often kiss walls! my depth perception went about 5 years ago and I struggle, I dont fancy having the mondeo kissing too many so for me, its a no brainer!