Hi all.

 

I've had my Xtrons headunit for some time and previously had a reversing camera hardwired.  It worked fine until the video cable failed in the gaitor to the boot lid.  I've just tried to install a wireless camera transmitter and receiver.

 

The camera and transmitter are wired perfectly, tested and working.

 

I have connected the wireless receiver to the wiring loom supplied with the headunit, which is connected to an external CAN-bus decoder.  Without a wiring diagram or supporting information, I connected the +ve wire of the receiver to a brown wire marked BACK-CAR, which is connected between the heanunit and CAN decoder, and spliced the -ve wire into the black ground wire in the loom. 

 

I tested this yesterday before hard-wiring and it worked fine - the transmitter was powered up and the headunit switched to the camera feed when reverse gear was selected.

 

Now that I have hard-wired it into the loom, the headunit does not detect reverse gear selection and there is not power to the transmitter.

 

Any ideas as to what's gone wrong?!

 

I must caveat:  At first today (but after the test) I accidently connected BACK-CAR to transmitter -ve and transmitter +ve to ground.  Could this have caused damage to the CAN decoder or headunit to prevent it from detecting reverse gear?

 

Thanks in advance.

 

Do you not mean "camera and reciever"?

 

You say the transmitter is not recieving power, the transmitter will be at the rear probably integrated into the camera, how have you powered this?

 

On my Octavia I took the power to the camera from the rear wiper permanent feed, it worked fine, doing the same on the Yeti worked but the camera LED's were shining white light to the rear all the time and not just when I engaged reverse gear so I had to wire it from the dedicated reverse camera feed on the head unit, this would not be possible on a wireless system but either the reciever must be wired to a feed only active when reverse is transmitted or the camera by tapping into the reversing lights themselves.

2 hours ago, J.R. said:

Do you not mean "camera and reciever"?

 

You say the transmitter is not recieving power, the transmitter will be at the rear probably integrated into the camera, how have you powered this?

I meant "camera and transmitter" at the back of the car are working fine.

 

The transmitter is not integrated with the camera, they're separate but powered from the same source, from the rear wiper as you have done.

 

I meant the receiver at the front of the car is not getting power - now, after wiring it in to the loom.

 

You mentioned a dedicated reverse camera feed from the headunit.  This is what I have tried to identify and wire the RECEIVER to, but there is not reference or manual for the unit that I can find.  I went on a hunch/guess based on the label "BACK-CAR".  Would you say this is correct?

 

I suspect power to the receiver is not at the root of the problem - the fact that the headunit doesn't switch to camera video input when reverse is selected suggests a CAN/decoder problem.

 

Thanks

 

The canbus recieving a reverse signal is not what switches the display to reversing camera, if it were it would bring up a blank display with trajectory lines even if no camera were fitted, its the presence of a video signal + probably an "and" logic requiring a reverse input from canbus that will bring up the display.

 

You say "I connected the +ve wire of the receiver to a brown wire marked BACK-CAR, which is connected between the head unit and CAN decoder, and spliced the -ve wire into the black ground wire in the loom. "

 

I had to guess also, sometimes the Ebay listing shows a wiring diagram, mine was labelled "R" it should be a bare unconnected dedicated wire leading from the head unit not one connecting the head unit to the canbus convertor but you may not have meant splicing into a wire.

 

You can test if the head unit is getting a reverse signal from the canbus, if you have parking sensors they should display, it should also mute the radio or satnav commands if programmed to do so.

 

From the way that you have wired the camera and transmitter it is transmitting a signal all the time, the head unit will be looking for a video signal to appear so you need to make sure that the reciever only operates when reversing, or the transmitter or both.

 

It was from having learned on the install how the head unit reacts I knew that a wireless rear camera would bring challenges. You could try hardwiring your video signal with a loose coax cable to see if it behaves then.

46 minutes ago, J.R. said:

The canbus recieving a reverse signal is not what switches the display to reversing camera, if it were it would bring up a blank display with trajectory lines even if no camera were fitted, its the presence of a video signal + probably an "and" logic requiring a reverse input from canbus that will bring up the display.

 

This is exactly what I've been seeing for the last 8 months since the old wired camera solution stopped working - a black screen with the trajectory lines.  On this basis, I believe it only requires the CAN bus signal to trigger it to switch to video and will happily do so without a video signal.

 

52 minutes ago, J.R. said:

You say "I connected the +ve wire of the receiver to a brown wire marked BACK-CAR, which is connected between the head unit and CAN decoder, and spliced the -ve wire into the black ground wire in the loom. "

 

See photo - the loose brown I've circled is a tap off a brown between headunit plug (left) and canbus decoder (right).  That wire did provide a +12V feed yesterday when I tested it.  I spliced the -ve wire from the receiver into the main ground wire between headunit and car wiring.

 

55 minutes ago, J.R. said:

You can test if the head unit is getting a reverse signal from the canbus, if you have parking sensors they should display, it should also mute the radio or satnav commands if programmed to do so.

 

Unfortunately I don't have parking sensors so there is no alternative mechanism to mute audio or switch display.  If there is another way of testing the CAN bus signal I'm all ears!  I've explored settings in the "factory settings" menu, changing canbus mode, deactivating/reactivating it, etc.  Still not joy.  

 

58 minutes ago, J.R. said:

From the way that you have wired the camera and transmitter it is transmitting a signal all the time, the head unit will be looking for a video signal to appear so you need to make sure that the reciever only operates when reversing, or the transmitter or both.

 

Yup, the video signal from the camera is always on with the ignition and the receiver should be powered up when the headunit is told to look for it by the CAN bus.  When I tested it yesterday, the power LED on the receiver was doing exactly this when selecting reverse, so it WAS working!! This is the most frustrating thing about this.  

 

The only thing that's changed since then is I've fitted bullet connectors on the ends of wires, and soldered a 'spur' wire, spliced into the ground wire.  And I connected the receiver the wrong way to start with... but I don't understand how this would have damaged the CAN decoder/headunit but maybe it has?

 

1 hour ago, J.R. said:

You could try hardwiring your video signal with a loose coax cable to see if it behaves then.

 

This might have to wait.  I don't have access to a long enough spare cable where I am currently isolated!

 

Thanks for your reply 🙂

So I have tested the camera and wireless transmitter & receiver by connecting to a different power source and video input on the headunit.  This part of the system is working as there is a camera image displayed on the headunit.

 

There is definitely a problem with the headunit detecting reverse gear, the CAN decoder passing the signal to the headunit, or the CAN bus itself not transmitting the reverse signal.

 

Can anyone suggest a way of testing any of the above?

 

Many thanks!

I already did.

 

There are many programmed features of your unit that if selected will react to reverse gear being engaged, radio muted, satnav muted etc. With them selected if your reversing lights work but the head unit functions do not react then your hypothesis may be correct but did you not say earlier that you have the reverse trajectory lines appear on the screen when you select reverse? If that is the case then the unit must know that reverse gear has been selected.

 

Did you try the wireless camera with a different power source to the correct reversing camera input on the head unit with reverse gear engaged?

 

2 minutes ago, J.R. said:

I already did.

 

There are many programmed features of your unit that if selected will react to reverse gear being engaged, radio muted, satnav muted etc. With them selected if your reversing lights work but the head unit functions do not react then your hypothesis may be correct but did you not say earlier that you have the reverse trajectory lines appear on the screen when you select reverse? If that is the case then the unit must know that reverse gear has been selected.

 

Did you try the wireless camera with a different power source to the correct reversing camera input on the head unit with reverse gear engaged?

 

Hi J.R.

 

No, I said that previously the unit was switching and displaying trajectory lines.  It always has done.  Up until a few days ago, when I wired up the wireless receiver the wrong way round. 

 

And now it does NOT switch source or display any trajectory lines, or seem to recognise that reverse gear is selected.

 

Yes, I have tried the wireless receiver on a different power.  It works on a different video input.  It does NOT work on the reverse camera input, because the unit does not switch to that source.  (The receiver does NOT power up when connected to the correct switched power source.)

 

 

Understood.

 

Nothing should have changed but I would go through all the programming options and also get the manufacturers acess code as there are lots of further settings there.

 

On my last head unit it was plug & play like yours is or was, the reverse camera just worked straight off, on this new one I did not have the trajectory lines but eventually got them working from a nonsensical translated option in some obscure menu.

 

I would persist in trying to find and select another programmed setting that would react to reverse gear being engaged, "beep on reverse" I think is one of them, its the best way to know for sure that your unit is or isn't getting the signal from the canbus, its a coded data string and not something that you can measure, I dont think you can have bloxn the comms because I assume it is still displaying other things, doors left open, heating etc.

 

Agreed, nothing should have changed, which is why I'm suspicious I may have damaged something in connecting the receiver the wrong way round, but I'm not sure how.

 

I'm also speaking with Xtrons tech support about it, vanely hoping they can shed some light on it!

 

If there is another trigger that would be brilliant, but I haven't come across anything obvious in either Android or Factory settings, yet.  As you said, the difficulty is often interpreting the ambiguous setting descriptions.

 

The headunit still displays AC info I think, not sure about doors, now.

 

Don't suppose low battery voltage could be anything to do with it, could it?  The car is standing and not being driven due to lockdown and I've run it flat a couple of times already...

I dont think the problem will be with canbus comms in that case.

 

I assume that the reversing lights are illuminating, that means that the body control module is sending the signal via the canbus to the rear light modules so it will be getting to the head unit if the aircon data etc is.

 

Re battery voltage, did you try it with the engine running?

 

Just had a play with mine, reverse camera displays with ignition on but engine not running however if I turn the key back to the auxiliary position it does not display, I also know that if I leave the ignition on too long without the engine running it eventually shuts down to the auxiliary power only.

Yes, I've checked reversing lights and they are illuminating on ignition and engine running.  So I've checked the issue with the engine running and the headunit doesn't switch to camera when reversing.

 

The headunit works on auxiliary power for a while (~10 minutes) after the ignition is turned off.  I think that the reverse camera only worked on ignition (which makes some sense, as nothing on the canbus needs to know the car's in reverse gear when the ignition is off), but that's no longer the case.

 

Thanks for your help 👍

Hope that you resolve it

Thank you.  I'll let you know if I get anywhere with Xtrons, but I suspect something is broken and I'll have to give up on it.  Annoying because I know the camera works and I've been missing it.

 

Also annoying is I've got OEM parking sensors and wiring to fit and now's a perfect time to do it, but I haven't got them with me or the right tools at the moment!

 

I am so sick of refitting the headunit though.  I find it really awkward with the amount of cables and limited access back there.  Oh, and my sub's blown too... (easy fix in the boot) 😔