Question 12v from reverse light not forcing HU into rear cam mode

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ludditefornow

Senior Member
Nov 29, 2017
321
107
Redmi K20 Pro
I have a Navifly 7862 head unit and up until now have not bothered to add a rear cam to integrate into the head unit. My car has a separate factory rear cam that has the monitor integrated into the rear vision mirror.

So due to a rainy weekend, I decided to add a new AHD cam. Cam is wired to the reverse light. My 6m RCA plus power lead at the head unit gets 11 volts when reverse gear is triggered. The RCA gets about 0.5 volts.

The options to connect to the 11 (12) volt red power to the head unit are wires called "Camera B+" (red), "IR" (grey), "Brake In" (pink) and two different unnamed yellow wires that are all running from the same connector from the head unit.

The 11 volt red power is connected to Camera B + yet when in reverse the head unit screen does not change. I have tried the live 11 volt line on IR, Brake In and the 2 yellow wires to try and get the head unit to switch to rear cam mode but I cannot get that to happen.

eve if the camera was faulty, I would expect to see the head unit change from home screen to a blank screen that states "no signal" or similar.

Can anyone suggest what the issue might be. I have looked through the settings but am yet to find anything to force the head unit to change to rear cam mode.
 

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rigattoni

Senior Member
Apr 27, 2010
1,694
540
Fuerth
I have a Navifly 7862 head unit and up until now have not bothered to add a rear cam to integrate into the head unit. My car has a separate factory rear cam that has the monitor integrated into the rear vision mirror.

So due to a rainy weekend, I decided to add a new AHD cam. Cam is wired to the reverse light. My 6m RCA plus power lead at the head unit gets 11 volts when reverse gear is triggered. The RCA gets about 0.5 volts.

The options to connect to the 11 (12) volt red power to the head unit are wires called "Camera B+" (red), "IR" (grey), "Brake In" (pink) and two different unnamed yellow wires that are all running from the same connector from the head unit.

The 11 volt red power is connected to Camera B + yet when in reverse the head unit screen does not change. I have tried the live 11 volt line on IR, Brake In and the 2 yellow wires to try and get the head unit to switch to rear cam mode but I cannot get that to happen.

eve if the camera was faulty, I would expect to see the head unit change from home screen to a blank screen that states "no signal" or similar.

Can anyone suggest what the issue might be. I have looked through the settings but am yet to find anything to force the head unit to change to rear cam mode.
Go to factory settings and find a setting called "Prohibit Reverse", switch this setting and try again.
 
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rigattoni

Senior Member
Apr 27, 2010
1,694
540
Fuerth
I have a Navifly 7862 head unit and up until now have not bothered to add a rear cam to integrate into the head unit. My car has a separate factory rear cam that has the monitor integrated into the rear vision mirror.

So due to a rainy weekend, I decided to add a new AHD cam. Cam is wired to the reverse light. My 6m RCA plus power lead at the head unit gets 11 volts when reverse gear is triggered. The RCA gets about 0.5 volts.

The options to connect to the 11 (12) volt red power to the head unit are wires called "Camera B+" (red), "IR" (grey), "Brake In" (pink) and two different unnamed yellow wires that are all running from the same connector from the head unit.

The 11 volt red power is connected to Camera B + yet when in reverse the head unit screen does not change. I have tried the live 11 volt line on IR, Brake In and the 2 yellow wires to try and get the head unit to switch to rear cam mode but I cannot get that to happen.

eve if the camera was faulty, I would expect to see the head unit change from home screen to a blank screen that states "no signal" or similar.

Can anyone suggest what the issue might be. I have looked through the settings but am yet to find anything to force the head unit to change to rear cam mode.
By the way...
You are forcing 12V into the Videosignal line... What are you doing there?
I just had a look at your attached picture. You should not wonder if the radio is now in the eternal hunting-grounds.

If you don´t know how to install a radio, please search for one who can do that without burning down your car. On top the 12V line just twisted together... Whow...Never seen someone doing such bad things in one single posting.
 

ludditefornow

Senior Member
Nov 29, 2017
321
107
Redmi K20 Pro
By the way...
You are forcing 12V into the Videosignal line... What are you doing there?
I just had a look at your attached picture. You should not wonder if the radio is now in the eternal hunting-grounds.

If you don´t know how to install a radio, please search for one who can do that without burning down your car. On top the 12V line just twisted together... Whow...Never seen someone doing such bad things in one single posting.
I have temporarily twisted the wire for testing purposes. I solder and heat seal connections when confirmed. Are you always this critical of people?

So what voltage should be fed to the Camera B + line?

The directions was to tap into the reverse light (which is 12 volt) and send that to the power line that runs parallel with the RCA. Are you suggesting that I shouldn't?

Well how about helping here instead of criticising, please, if you know better.
 

marchnz

Senior Member
Nov 26, 2012
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I have temporarily twisted the wire for testing purposes. I solder and heat seal connections when confirmed. Are you always this critical of people?

So what voltage should be fed to the Camera B + line?

The directions was to tap into the reverse light (which is 12 volt) and send that to the power line that runs parallel with the RCA. Are you suggesting that I shouldn't?

Well how about helping here instead of criticising, please, if you know better.

Not critical- post is accurate and suggests finding a skilled installer to assist you. Poking power on to the head unit wires without understanding is a sure way to break the unit or vehicle.
 
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ludditefornow

Senior Member
Nov 29, 2017
321
107
Redmi K20 Pro
Not critical- post is accurate and suggests finding a skilled installer to assist you. Poking power on to the head unit wires without understanding is a sure way to break the unit or vehicle.
There are 5 in lines to tap.

The literature that came with the cam as well as all videos online from the likes of Joying that I found show a 12v tap from the rear reverse light for the trigger.

You posted recently about 4PDA not being wanted at XDA because the silo knowledge.

Are you not willing to take a few minutes to actually share knowledge when there is a direct lack of knowledge from suppliers?
 

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ludditefornow

Senior Member
Nov 29, 2017
321
107
Redmi K20 Pro
Well I found the issue and somehow 'managed' not to destroy my head unit, my car, my house or the local power station.

All connections are nicely soldered and heat shrink wrapped now that I have a permanent fix.


The initial attempt at connecting the 12v line to Camera B + as noted on other how tos did not work.


To stay in the spirit of XDA (unlike the postings of some) I would like to advise that the wiring diagram from Navifly was incorrect.They have the pin 2 on the main connector as the reverse that feeds the CAN module. Pin 2 carries a constant 12v. Pin 3 (pink on my HU connector) carries zero voltage. I tapped pin 3 pink wire on the way to the CAN and added the red daughter wire on my 6m long RCA cable.



My red daughter wire is fed 12v from my rear reverse lamp. Reverse lamp also feeds the reverse cam.

I hope this assists someone in future.
 

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marchnz

Senior Member
Nov 26, 2012
4,898
1,004
NZ
Well I found the issue and somehow 'managed' not to destroy my head unit, my car, my house or the local power station.

All connections are nicely soldered and heat shrink wrapped now that I have a permanent fix.


The initial attempt at connecting the 12v line to Camera B + as noted on other how tos did not work.


To stay in the spirit of XDA (unlike the postings of some) I would like to advise that the wiring diagram from Navifly was

You did it. Thanks for posting your findings, I believe this has been posted about before.

I wouldn't recommend projecting at those that have actually spent hours to days developing methods, tools and helping others here.
 
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leo06

Senior Member
Dec 28, 2008
294
79
Patras
All that because of the canbus. i believe they send you a canbus box that only works for steering wheel buttons and nothing else. i had the same problem and solved it like you did.
 

rigattoni

Senior Member
Apr 27, 2010
1,694
540
Fuerth
To stay in the spirit of XDA (unlike the postings of some) I would like to advise that the wiring diagram from Navifly was incorrect.They have the pin 2 on the main connector as the reverse that feeds the CAN module. Pin 2 carries a constant 12v. Pin 3 (pink on my HU connector) carries zero voltage. I tapped pin 3 pink wire on the way to the CAN and added the red daughter wire on my 6m long RCA cable.
Sorry to say, but the wiring diagram is not really incorrect. It always depends on the aftermarket cam you use. But it is never a good idea to feed 12V into a CPU which just expects a video signal.
...and if you have a look at the wiring diagram of the camera, it shows 2 different ways to get the cam feeded with 12V.
The first one is the yellow connector which has a red wire coming out.
If you would have used this one, plug it into the "CAM IN" connector of your unit and the red one to the Back wire of your unit you would have been okay.
Using the back light to feed the camera is in most cases not necessary.

By the way... As I have seen that you feed the Video-In chinch-connector with 12V, I really was the meaning that you even don´t know anything about that what you did. I just gave the tip to search someone who knows what he does. I didn´t see any chance to start from scratch to teach you how to do.
I am on top really pissed if I see someone just wiggling cables together.
I just counted 1+1 and decided that I have to stop you doing strange things, which could lead to shorts and such things.

So... if it is working now as expected: Fine! ...and thanks for posting.
 

leo06

Senior Member
Dec 28, 2008
294
79
Patras
Sorry to say, but the wiring diagram is not really incorrect. It always depends on the aftermarket cam you use. But it is never a good idea to feed 12V into a CPU which just expects a video signal.
...and if you have a look at the wiring diagram of the camera, it shows 2 different ways to get the cam feeded with 12V.
The first one is the yellow connector which has a red wire coming out.
If you would have used this one, plug it into the "CAM IN" connector of your unit and the red one to the Back wire of your unit you would have been okay.
Using the back light to feed the camera is in most cases not necessary.

By the way... As I have seen that you feed the Video-In chinch-connector with 12V, I really was the meaning that you even don´t know anything about that what you did. I just gave the tip to search someone who knows what he does. I didn´t see any chance to start from scratch to teach you how to do.
I am on top really pissed if I see someone just wiggling cables together.
I just counted 1+1 and decided that I have to stop you doing strange things, which could lead to shorts and such things.

So... if it is working now as expected: Fine! ...and thanks for posting.
First, the diagram is incorrect and has nothing to do with the aftermarket cam. He didn't feed any 12v to video signal, the red wire is the trigger for the head unit to switch to reverse cam input, the 12v from the head unit is to feed the camera and doesn't need to be connected when you feed the camera from the reverse light. When you put the reverse the head unit must switch to reverse cam input if the canbus box is correct for your car, in this case and mines as well it isn't. The wire he shows came from the canbus box must have 12v when you put in reverse but no 12v
 
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rigattoni

Senior Member
Apr 27, 2010
1,694
540
Fuerth
First, the diagram is incorrect and has nothing to do with the aftermarket cam. He didn't feed any 12v to video signal, the red wire is the trigger for the head unit to switch to reverse cam input, the 12v from the head unit is to feed the camera and doesn't need to be connected when you feed the camera from the reverse light. When you put the reverse the head unit must switch to reverse cam input if the canbus box is correct for your car, in this case and mines as well it isn't. The wire he shows came from the canbus box must have 12v when you put in reverse but no 12v
Sorry, but you are wrong.
The head unit reacts on a voltage difference to switch to the back view camera. It´s not needed to have 12V feeded to the head unit.

CAM-IN from the head unit expects the video signal nothing else.
 

leo06

Senior Member
Dec 28, 2008
294
79
Patras
Sorry, but you are wrong.
The head unit reacts on a voltage difference to switch to the back view camera. It´s not needed to have 12V feeded to the head unit.

CAM-IN from the head unit expects the video signal nothing else.
Sorry, you are wrong. The cam in expects video and that what gets. The 12v from the head unit is to feed the camera but if you already feed the camera with reverse light not needed to be connected. If the canbus box worked properly, all will work too. Do you have the head unit and everything is working? The diagram is incorrect because the brake ctl is not the brake ctl but the reverse camera trigger
 
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ludditefornow

Senior Member
Nov 29, 2017
321
107
Redmi K20 Pro
You did it. Thanks for posting your findings, I believe this has been posted about before.

I wouldn't recommend projecting at those that have actually spent hours to days developing methods, tools and helping others here.
I searched thoroughly and did not find the answer. Why didn't you link me to the answer?

Based on your condescending and unhelpful posts to me, I don't see why projecting at you in this instance is not unwarranted. You had the answers and you chose to not assist. You siloed.

"Prohibit Reverse", was a total red herring and forced me to add more variables into my testing. I now had to test multiple software options and wiring config as well as the incorrect Navifly info very time consuming.

If you feel I need to be banned for calling out this condescending, repugent and unhelpful responses. Go ahead. I have helped more people in this site than I have received and frankly I don't want to be a part of something where your attitude is acceptable.
 
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    I have a Navifly 7862 head unit and up until now have not bothered to add a rear cam to integrate into the head unit. My car has a separate factory rear cam that has the monitor integrated into the rear vision mirror.

    So due to a rainy weekend, I decided to add a new AHD cam. Cam is wired to the reverse light. My 6m RCA plus power lead at the head unit gets 11 volts when reverse gear is triggered. The RCA gets about 0.5 volts.

    The options to connect to the 11 (12) volt red power to the head unit are wires called "Camera B+" (red), "IR" (grey), "Brake In" (pink) and two different unnamed yellow wires that are all running from the same connector from the head unit.

    The 11 volt red power is connected to Camera B + yet when in reverse the head unit screen does not change. I have tried the live 11 volt line on IR, Brake In and the 2 yellow wires to try and get the head unit to switch to rear cam mode but I cannot get that to happen.

    eve if the camera was faulty, I would expect to see the head unit change from home screen to a blank screen that states "no signal" or similar.

    Can anyone suggest what the issue might be. I have looked through the settings but am yet to find anything to force the head unit to change to rear cam mode.
    Go to factory settings and find a setting called "Prohibit Reverse", switch this setting and try again.
    1
    I have temporarily twisted the wire for testing purposes. I solder and heat seal connections when confirmed. Are you always this critical of people?

    So what voltage should be fed to the Camera B + line?

    The directions was to tap into the reverse light (which is 12 volt) and send that to the power line that runs parallel with the RCA. Are you suggesting that I shouldn't?

    Well how about helping here instead of criticising, please, if you know better.

    Not critical- post is accurate and suggests finding a skilled installer to assist you. Poking power on to the head unit wires without understanding is a sure way to break the unit or vehicle.
    1
    Sorry to say, but the wiring diagram is not really incorrect. It always depends on the aftermarket cam you use. But it is never a good idea to feed 12V into a CPU which just expects a video signal.
    ...and if you have a look at the wiring diagram of the camera, it shows 2 different ways to get the cam feeded with 12V.
    The first one is the yellow connector which has a red wire coming out.
    If you would have used this one, plug it into the "CAM IN" connector of your unit and the red one to the Back wire of your unit you would have been okay.
    Using the back light to feed the camera is in most cases not necessary.

    By the way... As I have seen that you feed the Video-In chinch-connector with 12V, I really was the meaning that you even don´t know anything about that what you did. I just gave the tip to search someone who knows what he does. I didn´t see any chance to start from scratch to teach you how to do.
    I am on top really pissed if I see someone just wiggling cables together.
    I just counted 1+1 and decided that I have to stop you doing strange things, which could lead to shorts and such things.

    So... if it is working now as expected: Fine! ...and thanks for posting.
    First, the diagram is incorrect and has nothing to do with the aftermarket cam. He didn't feed any 12v to video signal, the red wire is the trigger for the head unit to switch to reverse cam input, the 12v from the head unit is to feed the camera and doesn't need to be connected when you feed the camera from the reverse light. When you put the reverse the head unit must switch to reverse cam input if the canbus box is correct for your car, in this case and mines as well it isn't. The wire he shows came from the canbus box must have 12v when you put in reverse but no 12v
    1
    Sorry, but you are wrong.
    The head unit reacts on a voltage difference to switch to the back view camera. It´s not needed to have 12V feeded to the head unit.

    CAM-IN from the head unit expects the video signal nothing else.
    Sorry, you are wrong. The cam in expects video and that what gets. The 12v from the head unit is to feed the camera but if you already feed the camera with reverse light not needed to be connected. If the canbus box worked properly, all will work too. Do you have the head unit and everything is working? The diagram is incorrect because the brake ctl is not the brake ctl but the reverse camera trigger