I want to install a rear view camera; manufacturer, Auto Vox model, RVS TW

I'm hoping some of the master electricians can tell me from attached Jag 2000 S Type rear taillight wiring guide (see page 104 08.2)

where the hot wire for the rear backup lights is?

Regards

,

Peter

 

The rear tail lights, including the reverse light work on switched earths, not a switched live, the 12v live feed to the lights is constant.
So you will need a relay of some type to power the rear camera.

In addition if you have the NAV touch screen you can also tap into the RGB feed that comes from the NAV DVD drive in the trunk. Again a relay will be needed.
This is however an HTSC video signal not a PAL video signal, so you need to make sure what format the camera you are using has.
(They can also be a bit dark in some cases.)

 

Agreed. I'm not seeing any direct on/off source that could be tapped for the camera. It's possible adding a relay in the reverse light circuit may throw off the control of the lights, but am not really sure. We've had several examples of a blown fuse to one rear lighting circuit cause trouble in a different circuit, so who knows what would happen.

If you wanted to try it, look at the wire in the upper right corner of the diagram you posted. That's the switched ground signal to the reverse parking aid circuit. That would probably be the easiest spot to add a relay. I'd suggest backprobing an existing connector to temporarily try it first, versus cutting/splicing wires for a permanent installation.

I looked to see if there's anything coming from the transmission or PCM that could be tapped, but it appears all external communication is via a data bus.

 

Couple thoughts…

The LED used to illuminate the “R” indicator on the gear shift might work, you’d need to take a multimeter to it for testing.

If not, a metal contact switch for the gearshift being in “R” might be an eas=

 

The power-feed to illuminate an LED will not suffice to power a reversing camera.
I agree with the comments above by Mellow and Karl regarding the use of a relay.
Here some additional information regarding using a relay for that purpose for those, who need a helping hand:
Those relays are pretty cheap on ebay or aliexpress. I'd use a 12VDC relay, able to switch 10A.
Here is the diagram:

and I'd use an inline fuse holder with a blade fuse, 10A.

PS: That is actually exactly how I did it (can't remember if it was on my S-Type or X-Type) to get a suitable plus-power-source for my DTRL, when there was only a switched earth, which is quite unusual. (And I just saw a video about a Ford Model A, where the body of the car was not Minus, but Plus - hence. it's kind of like Back to the Future...)

 

Thanks to all for offering ideas.

 

What about a flyback (I think that's the term) diode? To suppress the back EMF from the relay coil.

Jaguar relays tend to include them but not all 3rd party ones do.

 

I just learned the English term from you (flyback diode), and I just looked it up: Suppressor diode probably describes the function better. I know this type of diode from my studies under it's German name (Loeschdiode). I know about the theory that this diode takes care (=eliminates) the voltage spike, which occurs when the power to a coil (inductive load) is suddenly cut off. But in praxis I never used a suppressor diode. Maybe I should have, but I also could not see a problem caused by not using this diode...

 

The voltage can get to a (perhaps) surprisingly high level and if electronics are nearby ... not good!

It's akin to a mini-induction coil...

 

Thanks Peter for your great explanation , its really help while im trying to Connect my camera with no chance , whats the name or model of the relay to be used with my 2008 S-Type ?

 

@Alex812: You are probably thinking currently of big relays as you find them in the Jag fuse box.
No need for anything that fancy:
I just typed "relay 12V 10A" into Aliexpress (or any source-platform of your choice) and there I find among the first currently:

https://www.aliexpress.com/item/1005...d=5kvOTSAkN1JL

I use those blue relays. In the listing above you find relays for several voltages - as said: 12VDC. And as you can see on the pictures, there are relays with 4 feet (pins) and 5. This seller calls the ones with 5 pins "Type C". That's what you want. One of those relays is AU$2.09. Check, what else you find. I'd buy a pack of 10 somewhere to save money. The 5 pin relays have both - the NO and the NC output, those with 4 only NO - you want 5 pins. And the reason as to why 5 pins: For above application you need only 4 pins. But the price is about the same as for 5 pins. And if you buy a 10-pack, and you need a relay next time for something else (eg 2 in a row for DTRL (Daytime running light) LEDs, you would want 5 pins). I wrote a thread of how to install DTRL (which switches itself off when low beam is switched on - which is a legal requirement).

 

Thanks Peter for your fast and kind response , What do you think about this relay on Amazon :

My problem is while I connected my camera power wire to the reverse light it keeps on all the time and the head unit shows the camera screen only and I cant do nothing while the car not in reverse , so do you think this relay will solve the problem ?

Thanks in advanced my friend

 

The amazon link points to an unsuitable relay. As I pointed out: A very simple and cheap relay will do. 10A is already over the top, 5A will do. You chose a 40A relay on Amazon. That is a.) wasted money and b.) possible problem in the future, if the relay is really resigned to have 40A in mind, as "the power of" 40A will "clean" the relay over time (=burn off residues on the relay-contacts), while the low Amp application at hand does not have the power to clean off those residues.

If you connect everything in line with my little schematic above, things should work. The issue is - as pointed out above - "Switched ground", which was normal on the Tin Lizzy back then, but these days you would expect switched battery plus, unless of course the designer of the whole electric system had a special reason to do it as it is now.

PS: I do not know, which Electronic Shops there are in the US, but that is kind of the place where you go to for that relay. In Germany it would be "Conrad", in Australia it would be "Jaycar" - plus of course there are Aliexpress and ebay.

 

Thanks for your great advice, the AliExpress link you sent doesnt work , can you please resend a new one .Thanks

 

what about if you just enter: https://www.aliexpress.com/
and then you enter the keyword: relay 12VDC 10A
There you should see heaps - different prices, different quantities.

 

Does that work ?

12V SPDT B_M Type C ?

 

Yes, that one. I looked for the same listing (same seller) just now on my computer and it was free postage to Australia. Don't know, if it is also free to the US.
As Mentioned before, my choice would be to order more relays - maybe there is somewhere else a listing for 10 relays, but that is obviously up to you.

 

So sweet of you

 

Hi Peter ,

I did install the relay , and unfortunately it is still the same issue , the camera still get power all the time even not in reverse and the other issue is that once I connect the camera wires the head unit shows the camera view and I cant use any other functions in the head unit at all until I disconnect the camera power wires .

Any advice ?

Thanks

 

Measure the voltages. Look at Electrical Guide. Almost everything is powered all the time but only on when switched to earth.