Ignition live for reverse camera on CANBUS

[theandywaite]

I have had an Xtrons Android head unit for a year or so now (absolutely brilliant by the way). I'm considering buying & installing a reverse camera.

 

With a CANBUS car (2008 B6 Passat), can the camera just be wired up to an ignition switched live? 

 

I know the "traditional" way of wiring up a reverse camera is into the reverse lamp.  When reverse is selected, the reverse light comes on.  Because the camera is hooked into the same wiring, it comes on also.  The camera sends signal to the head unit.  The head unit detects the signal and switches to the camera to show the driver.

 

But becase VW cars are CANBUS, the stereo "reads" whether it should show the camera or not from the CANBUS - so as I understand it the feed to the camera doesn't need to be switched.  Will having the camera on all the time the ignition is on be okay for the car + camera?

[Rustynuts]

23 hours ago, naxtek said:

 

But becase VW cars are CANBUS, the stereo "reads" whether it should show the camera or not from the CANBUS - so as I understand it the feed to the camera doesn't need to be switched.  Will having the camera on all the time the ignition is on be okay for the car + camera?

 

This presumes you're going to be using an OEM camera on an OEM head unit, coded to work correctly. What you're asking is more relevant to the type of reverse camera and the actual head unit you have fitted. Xtrons themselves might be better placed to tell you how their head unit expects signals from the reverse camera, and how to wire it to work correctly.

[theandywaite]

55 minutes ago, Rustynuts said:

 

This presumes you're going to be using an OEM camera on an OEM head unit, coded to work correctly. What you're asking is more relevant to the type of reverse camera and the actual head unit you have fitted. Xtrons themselves might be better placed to tell you how their head unit expects signals from the reverse camera, and how to wire it to work correctly.

 

The Xtrons unit has CANBUS decoder, and switches to reverse camera input when the car is put into reverse (although there's no camera plugged in).  I'm confident that the HU works based on CANBUS signals.  The camera input is composite CVBS (which as far as I'm aware is standard).

 

I've done a lot of research on this topic, but all the documentation recommends wiring into the reverse light, OR, if the vehicle is CANBUS enabled taking an ignition switched feed and then switching that using a relay off the reverse lamp.  I don't see any point in doing the relay bit through - why not just leave the camera powered?  Thus my question on whether simply wiring it into an ignition switched live (without the relay) would be OK.

Edited 27 August, 2018 by naxtek

[theandywaite]

Attached is the CANBUS recommended diagram.

Interestingly, in a small foot note they do recommend just using ignition switched live on cars with low voltage / PWM based circuits.  So maybe that means it would be fine?  But then why would they recommend the complex relay method...

[Rustynuts]

As said. They'd be better placed to answer that question.

[langers2k]

Might be worth looking at some of the newer genuine lowline cameras.

 

The latest headunits take a composite signal (might be CVBS) and are designed to connect to the reverse lights without interference.

[theandywaite]

1 hour ago, Rustynuts said:

As said. They'd be better placed to answer that question.

 

Not a particularly constructive or helpful comment. I notice you don't tell people asking about Columbus head units to "ask Skoda".

 

I am posting here because Xtrons support isn't the best and I was hoping to create a "public record" for other people seeking the same answer.

[Rustynuts]

7 hours ago, naxtek said:

 

Not a particularly constructive or helpful comment. I notice you don't tell people asking about Columbus head units to "ask Skoda".

 

I am posting here because Xtrons support isn't the best and I was hoping to create a "public record" for other people seeking the same answer.

 

This being a Skoda forum, I help people with Skoda units. That's pretty much what I do.

 

All I was pointing out was the fact that you're presuming that Xtrons use canbus signals to run their unit the same way that Skoda do with theirs, and that might not be correct. For specific information regarding Xtrons units, they would know better than most.

[langers2k]

11 hours ago, naxtek said:

Interestingly, in a small foot note they do recommend just using ignition switched live on cars with low voltage / PWM based circuits.  So maybe that means it would be fine?  But then why would they recommend the complex relay method...

 

Ideally a camera would only turn on when needed as they aren't designed to be on permanently.

 

The easiest method is a 'clean' reverse light where clean means no bulb monitoring or PWM.

 

Your passat will probably have bulb monitoring which can cause interference with aftermarket cameras. To resolve this, you can use a relay as xtrons suggested. It basically provides a 'clean' power feed from the ignition live but still only powers the camera when the reverse light is on due to the relay. Be warned, some users have experienced buzzing where PWM is used... I'm sure some have added a diode or resistor to fix the buzz but I can't remember the details.

 

PWM, 5v or low powered LED's are mentioned as they might not turn a 12v relay on, cause they relay to buzz or the extra load could trigger a bulb warning light.

 

Personally, I'd probably use a genuine camera assuming they are CVBS. If you want to stick with an aftermarket camera, I'd try feeding it directly from the reverse light. If it causes interference I'd try a either a relay or a feed from the reverse switch.

 

8 hours ago, naxtek said:

Not a particularly constructive or helpful comment. I notice you don't tell people asking about Columbus head units to "ask Skoda".

 

To be fair, given that it's beyond the knowledge or experience of many forum users, it's not a bad shout to contact the manufacturer. Rusty has spent more time than most with Columbus headunits so I doubt Skoda are able to answer many questions he can't...

[theandywaite]

8 hours ago, langers2k said:

 

Ideally a camera would only turn on when needed as they aren't designed to be on permanently.

 

That was my thoughts also - it feels like it's going to wear quicker being on all the time - but I'm conscious I'm making an assumption not based in evidence / fact.  Don't suppose you know any reasons why (e.g. the sensors have a limited life like a bulb / prolonged use has been known to cause overheating)?

 

8 hours ago, langers2k said:

 

The easiest method is a 'clean' reverse light where clean means no bulb monitoring or PWM.

 

Your passat will probably have bulb monitoring which can cause interference with aftermarket cameras. To resolve this, you can use a relay as xtrons suggested. It basically provides a 'clean' power feed from the ignition live but still only powers the camera when the reverse light is on due to the relay. Be warned, some users have experienced buzzing where PWM is used... I'm sure some have added a diode or resistor to fix the buzz but I can't remember the details.

 

PWM, 5v or low powered LED's are mentioned as they might not turn a 12v relay on, cause they relay to buzz or the extra load could trigger a bulb warning light.

 

Personally, I'd probably use a genuine camera assuming they are CVBS. If you want to stick with an aftermarket camera, I'd try feeding it directly from the reverse light. If it causes interference I'd try a either a relay or a feed from the reverse switch.

 

Thanks - that's helpful.  I will try this as I want to try a "dry run" anyway before I start taking trim panels off and running wires.

 

8 hours ago, langers2k said:

 

To be fair, given that it's beyond the knowledge or experience of many forum users, it's not a bad shout to contact the manufacturer. Rusty has spent more time than most with Columbus headunits so I doubt Skoda are able to answer many questions he can't...

 

Sure, I appreciate it's specialist although I don't think beyond the realms of what could be discussed on here.  Just hoping for input from people who've been there and/or input from auto electricians.

 

Also I'm not trying to throw into question Rustynuts contributions to the forum - they've probably helped me in the past with something or other over the past few years.  I just felt that they slightly misinterpreted what I was asking in this case and I read their second post as unnecessarily inflammatory (maybe I'm reading too much into it).

[Rustynuts]

17 minutes ago, naxtek said:

 

I just felt that they slightly misinterpreted what I was asking in this case and I read their second post as unnecessarily inflammatory (maybe I'm reading too much into it).

 

Yes, I think you are. Nothing inflammatory intended.

[theandywaite]

Okay - just wanted to update this thread to anyone else finding it in the future.

 

All fitted and working. A little out of my comfort zone but I took my time and installed with a relay. Ignition live feed by tapping into the accessory socket in the boot. Relay triggered by the reverse lamp wire. There's a grounding point each side of the boot for the negatives. Both the taps have a 1amp inline fuse.

 

The camera itself has bright white LEDs on it so it's a good job I made it switched rather than permanent - otherwise these would have been on permanently.

 

 

 

Only thing I wasn't sure about - where to safely mount the relay?

 

I ended up getting a plastic project box from an electronics shop to neatly house it, and then used double sided sticky to stop it rattling around behind the boot carpet. Not sure if anyone has any better ideas on that one?