Hi guys, need some bit of help about installing the DIY Parking Sensor that I've bought. I'm better off checking opinions first before installing it myself.

So, I bought a 4 Front and 4 Back Parking Sensor. Installation instruction says that I need to connect 3 wires to power up the tool box.

1 wire connects to ACC
1 wire connects to Reverse
1 wire connects to Foot Brake
then your normal Ground/Earthing Wire.

Based on a bit of research with the help of youtube and google. The most common installation of 4 Back Parking Sensor is:

Reverse Wire will be connected to the Reversing Light.

Having the above knowledge, I reckon the Foot Brake Wire can be connected to my Brake Lights?

With the ACC wire, I'm planning to connect it to either my Cigarette Lighter or the Phone connection. The Phone connection have an ACC cable which is unused on my car.

I have taken a look on the diagram of the car with the software workshop I got from the forum.

Do you guys reckon this is a good idea?

I'll be installing them this coming Sunday, so still have 5 days to really think about it.

Your replies and opinions will be greatly appreciated.

Thanks.

Edit:
Found an image that can explain everything easily.
http://images.esellerpro.com/2726/I/723/6/8pointinstall1800.jpg

That all sounds right as long as the Cigarette Lighter or the Phone connection is actually going to ACC and not constantly powered.

Also make sure you don't install the sensors too low otherwise they'll detect the ground and go off all the time. I'd assume the installation instructions show the minimum height allowed.

That all sounds right as long as the Cigarette Lighter or the Phone connection is actually going to ACC and not constantly powered.

Also make sure you don't install the sensors too low otherwise they'll detect the ground and go off all the time. I'd assume the installation instructions show the minimum height allowed.

Hhmm.. As a precaution, I'm looking to put a fuse somewhere. I just don't know to which cable to put it into.

I have a hunch to put it on the ACC cable? Or will it be for all of them?

I'm looking to tap it on this cable, the red dot:

http://i.imgur.com/3n1GJuA.jpg

and will be using one of these:

http://i.imgur.com/OZtnyEL.jpg

Here's a video of how they've used it.

https://www.youtube.com/watch?v=j4ARXHYBw8g#t=14

Now, I'm getting confused about the size of the cable. With the above picture, the cable wire size is 0.85mm2 (square millimeter). Now the ones available on SuperCheapAuto are only 6mm (http://www.supercheapauto.com.au/online-store/products/Power-Take-Off-6-Piece-Yellow.aspx?pid=299029#Cross), 4mm (http://www.supercheapauto.com.au/online-store/products/Power-Take-Off-6-Piece-Blue.aspx?pid=299028#Cross), and 3mm (http://www.supercheapauto.com.au/online-store/products/Power-Take-Off-6-Piece-Red.aspx?pid=299027#Cross).

http://i.imgur.com/lm8ZTfv.jpg

Are all of them bigger than the cable itself?

Seems I'm loosing my math mind here, and trying google to do a conversion of square millimeter to millimeter, and no go. -_-

This is where I'm going to be putting the cables.

(Also, BACK UP LAMP is the REVERSING LIGHT, is it?)
http://i.imgur.com/PKy9PLF.jpg

(And, STOP LAMP is the BRAKE LIGHT, right?)
http://i.imgur.com/PvQeZJ3.jpg

These connectors are very shit.

NEVER use them. Do it properly.

Mike

Can you tell me how "properly" is properly?

Thanks.

Strip and solder it. They can easily come loose and lose their connection

Strip and solder it. They can easily come loose and lose their connection

Thanks for that. I guess I better have my soldering iron ready.

What cable should I put a fuse on?

Thanks.

Thanks for that. I guess I better have my soldering iron ready.

What cable should I put a fuse on?


Thanks.

The 12v positive (usually red) cable.

Sorry for the hiatus.

I was just given the change to install them sensors on my car yesterday as uni finishes.

I haven't permanently drilled a hole yet for the sensors as I want to test them out first, specifically the main board/box for it.

It worked yesterday, but upon testing it out this morning, it doesn't work any more. I am not sure If I fried it or cables are not just properly connected. I haven't soldered them yet, I just went for the "twist and cover" for the meantime. I guess I'll be doing them some other time. I hope that it's just the cables needing soldering and not incorrect wiring or anything like that.

I've checked the fuse for my cigarette lighter as based on the circuit diagram, the phone ACC is piggy backing from the ACC of the cigarette lighter, and is still in tact. I've checked my brake fuse too and its all good. break lights all working, reverse light all working. So it really is giving me the conclusion that the main box is fried, i hope not.

I"ll update, just difficult cause I.m here at work.


The 12v positive (usually red) cable.

Which one? ACC, Reverse, or Brake cable?

EDIT:
Don't mind. I think I've understood what you were saying that's the ACC right?

I'm already thinking about it, might as well put FUSEs for all 3 cables each. How much fuse amp should I put for each? 10amps or 15amps?

EDIT:
Had about done thinking about the fuses to use, so went on and grabbed one of these from AutoBarn.

https://media.autobarn.com.au/media/catalog/product/cache/2/image/500x500/9df78eab33525d08d6e5fb8d27136e95/5/4/54420BL.jpg

then grabbed 15amps fuses for it.

https://media.autobarn.com.au/media/catalog/product/cache/2/image/500x500/9df78eab33525d08d6e5fb8d27136e95/E/L/EL03247_1.jpg

I might as well put all cables into fuses. Even grounding/earthing cable. Lol.

Fuse box update..

properly soldered (as much as I can). With heat tubes. Then covered again by pvc/electric tape...

http://i.imgur.com/pEWcFa5l.jpg

Question for you guys:

I know ground doesn't really need to have a fuse for it, but I thought "what the hell". It's already in there. My question is is the AMPs enough for them? Red is 10amps and blue is 15 amps on the pic.. Thank you guys..

Not sure if you need 15A or even 10A fuses here. Is the purpose of the fuse is to protect the sensor control box? I’m assuming it is. There is already a 15A fuse in the ACC line (from your picture).

Also the wire diametres (3mm, 4mm, and 6mm) have cross section areas of (7mm2, 12.5 mm2 and 28.7 mm2) which are bigger than the 0.85 mm2 you need (which is 1mm dia BTW). Anyway the thicker the wire the better for this. The maximum current draw for the 1mm dia wire is 9.5A so no point using the 15A (your wire will melt before the fuse blows).

I would look at the power rating or amperage rating on the control box and determine fuse size from there. If it’s 5A use a 5A fuse or lower. Convert a power rating to Amps (or milliamps) by dividing by 12 (volts) and use that.

Hope this is helps.

Not sure if you need 15A or even 10A fuses here. Is the purpose of the fuse is to protect the sensor control box? I’m assuming it is. There is already a 15A fuse in the ACC line (from your picture).

Also the wire diametres (3mm, 4mm, and 6mm) have cross section areas of (7mm2, 12.5 mm2 and 28.7 mm2) which are bigger than the 0.85 mm2 you need (which is 1mm dia BTW). Anyway the thicker the wire the better for this. The maximum current draw for the 1mm dia wire is 9.5A so no point using the 15A (your wire will melt before the fuse blows).

I would look at the power rating or amperage rating on the control box and determine fuse size from there. If it’s 5A use a 5A fuse or lower. Convert a power rating to Amps (or milliamps) by dividing by 12 (volts) and use that.

Hope this is helps.

I grabbed the wires from SupercheapAuto and they are stated to be 10amps wires. So yeah, 15amps are not good. So it should be 10amps or less. I think I actually just need a 5A or less. I'll check it out once back home, still at work. And yes, it is to protect the box and the car in any case.

And good thing I fixed it up. Apparently there's no problem on the box, everything seems to work fine after soldering the wires. Might be just loose wire that's why its not working before. I'll be drilling the sensors asap once back home.

Thanks for all the help guys..

I'm not an electrical engineer, but I imagine putting a fuse on ground is a bad idea. Let's say the ground fuse blows, now electricity has nowhere to go and will look for an escape. The purpose is the ground cable (other than to complete the circuit) is to ensure electricity flows out that way
I may be overthinking this since it's only a 12v system

I'm not an electrical engineer, but I imagine putting a fuse on ground is a bad idea. Let's say the ground fuse blows, now electricity has nowhere to go and will look for an escape. The purpose is the ground cable (other than to complete the circuit) is to ensure electricity flows out that way
I may be overthinking this since it's only a 12v system

You've actually got a point there.

Anyone else have any opinion on this?

Edit:
But for the ground fuse to blow, that means the system has already gotten a big amount of electricity which the other 3 fuses should have already picked up before even getting on the box?

I actually wrote this hours ago, but for some reason I lost access to this site before I could post it. Here it is anyway.

That's not how it works. With the circuit broken at the ground fuse, just like as if the positive fuses were to go, no current will flow. Zip, zero, zilch.

For a current to flow (this is true for any AC or DC circuit, but we're talking 12V DC car supply here), there must be a continuous, unbroken circuit between two points of differing electric potential (there must be a potential difference, also known as voltage) — eg: the poles on a battery. This potential difference allows electricity to "flow". The "direction" of the flow simply depends on your adopted convention, which is normally positive flowing to negative. Some people believe that it is actually the negatively-charged electrons that "flow" as the electric current, from negative to positive, but this is not the case (don't worry, I thought this too from my Year 7/8 science class days); both positive- and negative-charged particles and ions flow in either direction. Using the positive-to-negative convention is just one way to simplify this, as is always the reason of using such conventions in science. As an Engineering student, I use many conventions like this every day; I love them, they make my life so easy! :dancin:

The term ground comes from the fact that the power distribution systems are actually connected to the ground via long metal rods driven deep down into the earth. These ground points are connected to the neutral wires in the distribution system, which is considered the negative of AC circuits, with the live or hot wire being considered positive (again, a convention — but it's "worse" with AC, as not only is there positive and negative current flows like DC, but the current direction, according to the convention, is also oscillating with time). This is why the "negative" side of electric circuits is synonymous with ground or earth.

Provided there is not other grounding point in the parking sensor circuit, as in the only "negative" connection is through that wire, then there will be no current flow if the circuit is opened via the busted fuse. The problem with car circuits is that the entire metal chassis is an earth point, as the battery and "negative" terminal of the alternator (which actually generates AC, but this is converted into DC to both charge the battery and power the car's electrics while the motor is running) are both attached directly to the chassis. This is obviously intentional so it's not really a problem, but this is why one must be careful when working with car electrics and keeping wires properly insulated and clear from metal.

The problem with car circuits is that the entire metal chassis is an earth point, as the battery and "negative" terminal of the alternator (which actually generates AC, but this is converted into DC to both charge the battery and power the car's electrics while the motor is running) are both attached directly to the chassis. This is obviously intentional so it's not really a problem, but this is why one must be careful when working with car electrics and keeping wires properly insulated and clear from metal.

My favourite trick is removing a starter motor without disconnecting the battery, and you accidentally bump both poles of the solenoid on the chassis. Way more effective than coffee, much louder too

I actually wrote this hours ago, but for some reason I lost access to this site before I could post it. Here it is anyway.

That's not how it works. With the circuit broken at the ground fuse, just like as if the positive fuses were to go, no current will flow. Zip, zero, zilch....

Thanks for all that mate! I will fix it up asap! But I'm still thinking about replacing my trailer plug with the ones with reel switches on them. That way, I'll connect the ground cable of the parking sensor to the reed switch, so when a trailer is connected, the parking sensor is automatically off. wouldn't be giving me headaches of it detecting the trailer. But will think about the budget, this project is getting a bit more pricey than what I've originally planned. Money constraint.

Edit:
Or I could just buy an on-off switch and connect it to the ACC of the parking sensor.. -_-

Anyone knows the cheapest trailer plug with reed switch on it?

Looking at Narva's selections: http://www.narva.com.au/products/browse/flat

Is the parking sensor a closed or open circuit?

From Narva's own product description:

7 Pin Flat ‘Quickfit’ Trailer Socket with Reed Switch for use with Normally Closed Circuits

For use on vehicles with reversing sensors. The reed switch deactivates the reverse sensor while the trailer is connected. Suits all vehicles with normally closed circuits including Holden, Hyundai and After Market parking aids.

Although the above is just "general information" from them and may not apply to you, let me try to explain how it should work.

A "normally closed" (NC) circuit element means that, under normal conditions (hence the name), the circuit is closed and current is allowed to flow. When the right conditions are met, ie: non-normal conditions, then the circuit swaps its state (becomes open and no current can flow). In other words, an NC element is a normally "on" element.

In the case of a normally open (NO) circuit element, the settings are reversed: normally the circuit is "off", but when activated the circuit is "on".

Think of the push button on your PC or laptop. It is a NO push button. When you push it in for the brief second, it closes the circuit and allows current to flow. The computer detects this current and interprets that current as meaning you want to turn it on (or turn off / sleep / hibernate if already on, depending on your settings). Instead of relying on external mechanical input to activate the switch (pushing it), a reed switch uses magnetism to pull/push the switch contacts together/apart.

In the case of your circuit, you would want a NC reed switch. When the trailer plug cap is closed, the reed switch is closed (normal condition) and current flows. When you open the flap and connect a trailer (non-normal condition), the circuit is opened and no current flows — the reverse parking sensors are deactivated and you won't have useless beeping in reverse.

The following very basic diagram is what you have now:
http://i1048.photobucket.com/albums/s367/TehHyphen/AMC/revnoreed_zps3442aa47.png~original

By adding the reed switch in the circuit, you get this (normal condition vs non-normal condition):
http://i1048.photobucket.com/albums/s367/TehHyphen/AMC/revwreed_zps15ae28ad.png~original

Hence why you need an NC reed switch system.

By the way, assuming you take your ground wire from your little fuse box to the reed switch, all you are doing is adding another fuse between the "Sensor system" and the "Reed switch". Basically, it's redundant. Due to small inaccuracies in the "detection" of fuses (they work by breaking when they get too hot, which is designed to happen at the given amperage or current level) one fuse will break before the other. The circuit doesn't care which one blows; if one goes, it all stops.

From Narva's own product description:


Although the above is just "general information" from them and may not apply to you, let me try to explain how it should work.

A "normally closed" (NC) circuit element means that, under normal conditions (hence the name), the circuit is closed and current is allowed to flow. When the right conditions are met, ie: non-normal conditions, then the circuit swaps its state (becomes open and no current can flow). In other words, an NC element is a normally "on" element.

In the case of a normally open (NO) circuit element, the settings are reversed: normally the circuit is "off", but when activated the circuit is "on".

Think of the push button on your PC or laptop. It is a NO push button. When you push it in for the brief second, it closes the circuit and allows current to flow. The computer detects this current and interprets that current as meaning you want to turn it on (or turn off / sleep / hibernate if already on, depending on your settings). Instead of relying on external mechanical input to activate the switch (pushing it), a reed switch uses magnetism to pull/push the switch contacts together/apart.

In the case of your circuit, you would want a NC reed switch. When the trailer plug cap is closed, the reed switch is closed (normal condition) and current flows. When you open the flap and connect a trailer (non-normal condition), the circuit is opened and no current flows — the reverse parking sensors are deactivated and you won't have useless beeping in reverse.

The following very basic diagram is what you have now:
http://i1048.photobucket.com/albums/s367/TehHyphen/AMC/revnoreed_zps3442aa47.png~original

By adding the reed switch in the circuit, you get this (normal condition vs non-normal condition):
http://i1048.photobucket.com/albums/s367/TehHyphen/AMC/revwreed_zps15ae28ad.png~original

Hence why you need an NC reed switch system.

By the way, assuming you take your ground wire from your little fuse box to the reed switch, all you are doing is adding another fuse between the "Sensor system" and the "Reed switch". Basically, it's redundant. Due to small inaccuracies in the "detection" of fuses (they work by breaking when they get too hot, which is designed to happen at the given amperage or current level) one fuse will break before the other. The circuit doesn't care which one blows; if one goes, it all stops.

Thanks for all the help mate!

I am really going to be disconnecting the fuse for the ground cable. And if I will be ever getting one of the trailer sockets with reed switch on them, I will connect the ground cable on it directly, fuse-free.

Seeing that I'm not really into spending additional money for it (for the mean time), I'm just going to be getting one of those on-off switches. Which cable is preferable to put it? ACC Cable or Ground cable (almost same as a reed switch concept). OR is there any ONE button on-off switch but disconnects two cables?

Edit:
Guess I need a DPST switch to connect the ACC and ground on a single switch.

DPST = Double Pole, Single Throw. This simply means that two separate connections are managed by a single mechanism, just like two regular switches activated by the same rocker. So yes, you would be right in using a DPST switch for that application.

However, using a DPST switch like this — on both ACC and GND wires — is again redundant and unnecessary. The main computer of the device runs off the ACC signal, which requires a ground to complete its circuit (just like I mentioned before). Switching either ACC or GND will achieve what you want, there's no need to switch both, as the break in the circuit will stop all current flow to the system's computer. Doing this though will turn the whole system off altogether.

I suggest installing a switch to the reverse sensor wire instead (the one coming from the "reverse gear switch" into the sensor box from the diagram supplied by the manufacturer on your OP), as this will deactivate the reverse sensors only, just like the reed switch would, but obviously manually rather than automatically. This would also keep the front sensors working, which is the overall desired outcome anyway.

If you were in Victoria (or I in WA), I would drop in to visit and help you :)

DPST = Double Pole, Single Throw. This simply means that two separate connections are managed by a single mechanism, just like two regular switches activated by the same rocker. So yes, you would be right in using a DPST switch for that application.

However, using a DPST switch like this — on both ACC and GND wires — is again redundant and unnecessary. The main computer of the device runs off the ACC signal, which requires a ground to complete its circuit (just like I mentioned before). Switching either ACC or GND will achieve what you want, there's no need to switch both, as the break in the circuit will stop all current flow to the system's computer. Doing this though will turn the whole system off altogether.

I suggest installing a switch to the reverse sensor wire instead (the one coming from the "reverse gear switch" into the sensor box from the diagram supplied by the manufacturer on your OP), as this will deactivate the reverse sensors only, just like the reed switch would, but obviously manually rather than automatically. This would also keep the front sensors working, which is the overall desired outcome anyway.

If you were in Victoria (or I in WA), I would drop in to visit and help you :)

Thank you so much for the offer mate. Really appreciate it. I guess I would just rather go for the manual switch and connect it to the ground cable as that's the one that I need to disconnect from the fuse box. Less work.

If ever I will be able to get a different trailer socket with reed switch, which I doubt I will, I'll be connecting the ground cable to it directly, without the fuse.

I really wasn't going to bother connecting the front sensors anymore. It'll be a lot more work specially working the cable all the way around the spacings of the bonnet part. going back to the boot, which I've got the box located. For now, the reverse sensor should suffice.

Thanks for all the feedback guys. Really appreciate it.

Not sure if you need 15A or even 10A fuses here. Is the purpose of the fuse is to protect the sensor control box? I’m assuming it is. There is already a 15A fuse in the ACC line (from your picture).

Also the wire diametres (3mm, 4mm, and 6mm) have cross section areas of (7mm2, 12.5 mm2 and 28.7 mm2) which are bigger than the 0.85 mm2 you need (which is 1mm dia BTW). Anyway the thicker the wire the better for this. The maximum current draw for the 1mm dia wire is 9.5A so no point using the 15A (your wire will melt before the fuse blows).

I would look at the power rating or amperage rating on the control box and determine fuse size from there. If it’s 5A use a 5A fuse or lower. Convert a power rating to Amps (or milliamps) by dividing by 12 (volts) and use that.

Hope this is helps.

I don't really know on how to compute for the amp that I need. These are all the information that I can gather:
- Rate voltage:12V
- Operation voltage:10.5-16v
- Rated current:40-300mA

I'm pretty sure I'm wrong with this, but, if I base it to the rated current then that means I need less than an amp to make it still work...?



DPST = Double Pole, Single Throw. This simply means that two separate connections are managed by a single mechanism, just like two regular switches activated by the same rocker. So yes, you would be right in using a DPST switch for that application.

However, using a DPST switch like this — on both ACC and GND wires — is again redundant and unnecessary. The main computer of the device runs off the ACC signal, which requires a ground to complete its circuit (just like I mentioned before). Switching either ACC or GND will achieve what you want, there's no need to switch both, as the break in the circuit will stop all current flow to the system's computer. Doing this though will turn the whole system off altogether.

I suggest installing a switch to the reverse sensor wire instead (the one coming from the "reverse gear switch" into the sensor box from the diagram supplied by the manufacturer on your OP), as this will deactivate the reverse sensors only, just like the reed switch would, but obviously manually rather than automatically. This would also keep the front sensors working, which is the overall desired outcome anyway.

If you were in Victoria (or I in WA), I would drop in to visit and help you :)

I bought one of these from autobarn: https://www.autobarn.com.au/narva-switch-rocker-12v-on-off-led-red-62003bl

https://media.autobarn.com.au/media/catalog/product/cache/2/image/500x500/9df78eab33525d08d6e5fb8d27136e95/6/2/62000_1.png

And based on the packaging, there are three connectors for it: PWR (12v Battery or ACC connection, I think), ACCessory, and Ground.

I'm thinking about using this switch on the GROUND cable that I have. As far as I can understand on how the switch works, is that when it is ON, then it connects the pwr to acc, is that right? ground basically is just ground. Translating this to what I need to happen, is that I connect MY GROUND cable to ACC right? isn't that going to be connecting my ACC to my ground then (based on how I understood it), which I think is bad?

How can I connect my ground cable to the switch, while keeping the LED light on if its ON? or is just going to be easier to connect the switch to MY ACC then?

"if I base it to the rated current then that means I need less than an amp to make it still work..."

That is correct - looks like maximum current through the control box is 300mA - see if you can get a fuse that meets is 300mA that (probably an inline glass fuse) ie, it will blow first rather than your control box.

After reading through the description of some of Narva's switch products on their website, they have a bit of their own wacky code going on.

Power = source side. This could be either constant +12V or ACC feed. As long as it's the "positive" feed.
Acc = component/device/accessory side. This is the side you connect your sensor system to.
Ground = ground connection for the activation LED only. Normal switches (without the light) do not have this pin. Without this pin connected to ground, the LED will not perform its on/off display function, but the switch will still work.

Now, as I have stated before, breaking a circuit with a switch in the off position means no current flows. With this in mind, it does not normally matter which pins you connect to your devices; you could connect your source to the Acc pin and the device to the Power pin, and you wouldn't be able to tell the difference as the circuit would behave the same. The reason for specifying source and device pins is to keep consistency, as car electrics can be very complicated — for example: positive can be any number of wire colours; ground is usually black or black/white, but not always; wire lengths, the physical path taken by the wire such as through grommets, brackets, etc, and the vast number of wires can make it difficult to track their function and where they come from if you forget. Therefore, it's wise to wire it up as indicated, especially if anybody else has to deal with it in the future.

Because you have an LED light in the switch, it may be important that the source and device wires are connected to the right pins. This is because it is likely that the LED will receive its power from the source pin. As I am sure you know, LED stands for Light Emitting Diode, and all different forms of diodes have the same property: they allow current to flow in one direction (forward bias), and block it, up to a certain level, in the other direction (reverse bias). LEDs will only light up when connected in forward bias. Depending on how the switch is wired internally, it may be necessary for the pins to be wired correctly (especially the ground pin!). I suggest you wire it up as instructed by Narva.

As for the current, RonRabbit is correct. The system's control box is rated for that current range, so that's what you need to work with. Using a 10A or 15A fuse is orders of magnitude too large for the box (provided those values are in fact for the control box), and the box would break well before the fuses blow. The voltage parts refer to the fact that it is designed to run on 12V, but will accept 10.5 to 16V as an input just fine. Please note that although car circuits are described as 12V, this is the voltage of the battery. When cars are running, the electronics utilise the alternator instead (which also charges the battery at the same time) — the battery is there to supply power to the starter motor to start the car, and to power all the "off" circuitry, such as lights, security systems and central locking, and maintaining volatile data in the ECU/other computers and headunits like clock times (which is why you need to reset everything after you disconnect the battery). Car alternators typically output a voltage around 14.4V instead, but they are capable of much more — this is maintained by the voltage regulator on the alternator.

Thanks for all the help guys!

http://i.imgur.com/nzsz2wc.jpg

I forgot to post the pic. It was put on the car a few days ago.

I still haven't fixed the fuse box (replace it with 300mAmp fuse, add the switch) and the ground cable (disconnect from the fuse box) though. That's the next thing I'll do.




Because you have an LED light in the switch, it may be important that the source and device wires are connected to the right pins. This is because it is likely that the LED will receive its power from the source pin. As I am sure you know, LED stands for Light Emitting Diode, and all different forms of diodes have the same property: they allow current to flow in one direction (forward bias), and block it, up to a certain level, in the other direction (reverse bias). LEDs will only light up when connected in forward bias. Depending on how the switch is wired internally, it may be necessary for the pins to be wired correctly (especially the ground pin!). I suggest you wire it up as instructed by Narva.

I guess it's safe to say that I'll just put the switch on the ACC cable then.

I'm planning to connect the 12v ACC to the Power Connector, ACCessory connector to the RPS box, then ground to ground. You think that's a good idea?

Edit:
This is the lowest amp fuse that I've found:

https://www.autobarn.com.au/narva-fuse-glass-3ag-1amp-blister-pack-52301bl

http://www.supercheapauto.com.au/online-store/products/SCA-Glass-Fuse-250V-1-25Amp.aspx?pid=291244&menuFrom=40105#Recommendations

Are they the lowest ones available from the market?

That's exactly how you should wire it.

Looks pretty good. I have a question about the sensors in the bumper, so i guess you drilled holes into the bumper bar (through the bumper cover)? What all the way through? How did that go, any issues?

Looks pretty good. I have a question about the sensors in the bumper, so i guess you drilled holes into the bumper bar (through the bumper cover)? What all the way through? How did that go, any issues?

Did encouter a few issues about it:
1. The two sensors on the far end, on both sides, just barely missed the metal bumber reinforcement.
2. The two sensors in the middle side is about the same. A bit fortunate that the sensor locations didn't hit any screws.
3. The cables of the sensor, avoiding unnecessary loops, avoiding the muffler, etc.

I had to buy a drill bit designed for metals from bunnings. And the corresponding drill for it. Costed me about $50.

Initially, I thought of putting it below the line of the bumper lining (just below the bumper reinforcement). Refer to the picture.But I've thought hard on it. Because the lining sits just below 50cm, which the sensors are ideally to be placed in between 50cm-70cm above ground (mine is sitting approx. 55-57cm from the ground). And the height will also adjust when people are in the car, so you would have to take that in consideration.

As far as I can remember, I tried to find first the center of the bumber (using the help of the tow bar), from the middle I've measured 25cm to the left and to right (these are the two sensors in the middle of the bumber). Then from them, I measured 44cm for the far end sensors. Initially I thought of making the distance between them equal, but I've contemplated a long time (days) about this and observed other cars as well. Sensors with equal distances between them often times are the cars without the two bar, cars with tow bars on the other hand always seem to have an added distance between them. Probably for the sensor to not pick up the tow bar and give false alarm? It might also depend on the RPS as well, I just opted in on my hunch.

The cable is another story, I tried my best to make sure the the cable will not be sticking in to something that might make it hot/melt, and avoiding unnecessary connections, etc. (you get what I mean). I had to make sure that the cables from the far right hand side sensors are all together with the one on the far left end side. I made sure that the cables are not BELOW the tow bar but OVER it, bumper reinforcement, and other stuffs behind the bumper. Because looking at the boot of the car, there is only one hole already there for the cables to get through, on the far left hand side, also realized that I was fortunate to sit the RPS box on the left of the boot. I do not want to drill any holes anymore so I took advantage of this, and really just spent more time than expected.

As of today, haven't had any problems with it so far. I've been testing it almost every time I drive the car, and its all sweet!

But all in all, I reckon I did a good job for a newbie. All thanks to everyone here! Cheers to all of you!

I've got another question for you guys. I don't know which one to buy. Either Time-Delay fuse, or Fast Blow..?

Slow blo (time delay) (http://m.ebay.com.au/itm/171418388318?nav=SEARCH&varId=470456341312)

Quick blow (http://m.ebay.com.au/itm/181472733544?nav=SEARCH&varId=480437215273)

And what does the AG (http://m.ebay.com.au/itm/271148294645?nav=SEARCH) or M205 (http://m.ebay.com.au/itm/281437668448?nav=SEARCH) fuses means?

Or I guess I should be asking, which one is ideally for the RPS box? Thanks. I'm looking to replace the fuse after new year.

Thanks guys.

Anyone..?

Please..?

:(

I am not certain on what AG actually stands for (I think I remember it being All Glass or Automotive Glass, but I could be wrong), but it refers to standard sizing of small glass/ceramic fuses in that form factor. Similarly, M205 refers to the sizing, but is a metric sized fuse (a fuse 20 mm long and 5 mm in diameter), which, as most metric measurements do, makes considerably more sense than imperial (AG) sizing. Either AG or Mxxxx fuses will work for you, as you are making a custom circuit, but you will have to find an appropriate holder for them. Please refer to this table (http://i.stack.imgur.com/YD0yl.png) for a basic understanding and this PDF (http://www.littelfuse.com/industries/telecom/fuses/~/media/automotive/datasheets/fuses/automotive-aftermarket/glass-fuses/littelfuse_aftermarket_glass.pdf) for more indepth information about these fuses and their sizes.

The difference between fast-blow and slow-blow or time-delayed fuses is in the name: fast-blow means that the fused breaks as soon as its rated current is exceeded, whereas a slow-blow will allow surges of current above its rating, but will blow after extended periods of high current. When slow-blow fuses go depends on the makeup of the fuse itself, and the current supplied (a 630 mA fuse, for instance, will allow a constant 640 mA current to flow longer than a 1 A current). In your case, you would probably want to use a fast-blow fuse, as you are working with the maximum rating supplied by the manufacturer. Although it is likely tolerances and other factors will allow the box to handle more than 300 mA, you will still want your circuit to be within the manufacturers specifications.

Also, it is important to know that fuses are not perfect devices, and their performance can be affected by many factors, including ambient temperature. For example, fuses used in an ambient temperature of 25 °C are typically run at a maximum of 75% of their rated current to avoid what is called nuisance blowing, where the fuse (annoyingly) blows below its designed parameters — eg: a 10 A fuse is run up to 7.5 A under normal conditions to avoid it blowing all the time. Basically, the fuse rating is determined in a laboratory under set conditions, and when these conditions change, the fuse's performance changes; a fuse that runs in hot conditions will have a shorter lifespan than one in colder conditions. This is going way deeper than you really need to know, and you're probably learning more about fuses than you ever really wanted. Using a 300 mA fuse will be fine to protect your circuit, but you may have to replace fuses more often than you need to.

This is a very important question though: do you have a multimeter, and do you know how to use one? When building one's own or modifying electrical circuits, multimeters are a must have as they are so useful for troubleshooting. It might be a good idea to check the current flowing into the sensor box as it is without the new fuse, just to see what current you are dealing with at the moment.