How to disable the rear view mirror monitor

[JMod45]

I installed the backup camera re-route kit from infotainment in my truck about a month ago. Had to do a minor soldering fix when installing, but has worked great since then. I like having the image in the radio, but the screen lighting up inside my mirror just annoys me.

I had to back into my garage last weekend with the tailgate down. Radio, I could just switch to the cargo cam, but the mirror kept showing me the ground flying by on half the screen, which was the final push to make me try and disable it.

I started by removing the two video signal wires going to the mirror. This did stop the video feed, but when I put it in reverse, the mirror monitor lit up with a "No signal" picture (radio still showed the camera image correctly). Which still blocks a large section of the mirror, and not what I was after.

Did a quick google search, and found a mirror wiring diagram, so I made a guess using wire colors.

Orange wire with a purple tracer is labeled "LIN BUS CBC2", disconnected it, and everything was as I had hoped. Mirror doesn't know it is in reverse, therefore the monitor never even lights up. Radio still shows the camera image.

The microphone still works, but I didn't check anything else. Auto dimming should be internal and unaffected, and I can't bring myself to push the 9-1-1 button. Might try the assist this evening and see what happens. I do not have the rain sense wipers, or auto dim feature, these could be affected by that wire.

I used a sharpened paper clip to remove the pin connector on the harness from infotainment, and the put heat shrink over the exposed pin. I reconnected the video feeds to the mirror, as the monitor isn't powering up anyway. If I ever want to put the image back in the mirror, I just have to pull of some heat shrink, and plug the pin back into the connector. I chose to make all changes on the infotainment harness, so that all of the OEM wires and plugs are 100% unmodified.



Took off some extra wires for practice first. So there are 3 missing in the picture. Middle one is the only one that needs to be disconnected.




This is all on a 2014 Ram 2500 with the 8.4 inch radio, and required software according to infotainment.com

 

[JMod45]

Does anyone know how the "LIN BUS CBC2" wire works? I didn't put a meter on it, but guessing it is some form of communication wire. Things aren't as simple as 12v relays anymore.

Would be cool to wire a manual switch to that wire so I could see the camera feed in the mirror while driving if I ever wanted to.

 

[Jimmy07]

The linbus wire is what makes the camera turn on by knowing when the truck is in reverse. It also controls the rain sensor, automatic high beam sensor, 911/assist, and auto dim. As you found out, just eliminating that wire going to the mirror will solve the issue of the mirror screen turning on. Now, if you wanted to make all the other mirror features functional, you need to use that wire, but the BCM needs to be programmed to know that it has a radio using the camera image on the screen instead of using the mirror for the image.

 

[JMod45]

The linbus wire is what makes the camera turn on by knowing when the truck is in reverse. It also controls the rain sensor, automatic high beam sensor, 911/assist, and auto dim. As you found out, just eliminating that wire going to the mirror will solve the issue of the mirror screen turning on. Now, if you wanted to make all the other mirror features functional, you need to use that wire, but the BCM needs to be programmed to know that it has a radio using the camera image on the screen instead of using the mirror for the image.

I was concerned that wire may disable those, but I've never used the mirror buttons for anything other than troubleshooting, and my last two cars had some form of them. So in my case, it doesn't bother me. My radio already knows it has a camera in it, as it has always lit up when going into reverse, but only showed the cargo camera. The infotainment harness addresses that issue by having you switch the inputs when plugging in the harness.

I will definitely check out the assist button tonight, and see if it still functions. Only reason I think it might, is that I have other wires going through this harness, that weren't on the infotainment wiring diagram.

This is definitely a "do at your own risk" change, especially if it disables 911 functionality.

 

[JMod45]

Confirmed last night that the LINBUS wire disables the other mirror functions just as @Jimmy07 said. I've never needed a 9-1-1 button on a vehicle before, but as the saying goes "Better to have it and not need it, then need it and not have it" so I went ahead and plugged the LINBUS wire back in.

Since that takes out the easy way of disabling the mirror monitor, I had to do it the hard way. I get too focused on what I'm doing to ever remember pictures, but I got one at least.



I removed the mirror from the windshield, (youtube this, its easy, but a different style of bracket) then took it to my workbench. I've changed out a few cell phone screens and internals, so I have a kit to keep from marring plastic as long as you are careful. Using the plastic separators, I was able to remove the plastic mirror housing. The little plastic around the glass is inside the bigger plastic in the back. Wish I had a picture, but if you are interested in opening the mirror and need help, let me know and I can get more detailed on how to remove it.

I actually ended up disconnecting both sides of the wire and removed it so there isn't anything left inside to rattle.

Now everything works, and I don't have a screen blocking half of my mirror when I need it. I'll probably never act on the thought, but since I've now seen the inside of the mirror, I would be curious if a separate wire could be run to use the monitor for something.

 

[Jimmy07]

Confirmed last night that the LINBUS wire disables the other mirror functions just as @Jimmy07 said. I've never needed a 9-1-1 button on a vehicle before, but as the saying goes "Better to have it and not need it, then need it and not have it" so I went ahead and plugged the LINBUS wire back in.

Since that takes out the easy way of disabling the mirror monitor, I had to do it the hard way. I get too focused on what I'm doing to ever remember pictures, but I got one at least.



I removed the mirror from the windshield, (youtube this, its easy, but a different style of bracket) then took it to my workbench. I've changed out a few cell phone screens and internals, so I have a kit to keep from marring plastic as long as you are careful. Using the plastic separators, I was able to remove the plastic mirror housing. The little plastic around the glass is inside the bigger plastic in the back. Wish I had a picture, but if you are interested in opening the mirror and need help, let me know and I can get more detailed on how to remove it.

I actually ended up disconnecting both sides of the wire and removed it so there isn't anything left inside to rattle.

Now everything works, and I don't have a screen blocking half of my mirror when I need it. I'll probably never act on the thought, but since I've now seen the inside of the mirror, I would be curious if a separate wire could be run to use the monitor for something.

LOL. That’s one way of going about it. Good work. While you won’t get an actual check engine light, or it won’t bother anything, I’m curious if there would be any communication faults stored in the BCM since the rear view mirror image isn’t actually “programmed” out of the equation.

 

[JMod45]

LOL. That’s one way of going about it. Good work. While you won’t get an actual check engine light, or it won’t bother anything, I’m curious if there would be any communication faults stored in the BCM since the rear view mirror image isn’t actually “programmed” out of the equation.

I watched for a CEL first thing after hooking it up. lol.
I wish I knew what all of the wires were in that connector, but not having a lot of luck searching, even generic ones. I'm hoping that the actual display doesn't offer any feedback, and all of those wire are just inputs and power to the display, leaving the BCM believing that all is still working. Not sure if any apps would let me check for communication faults. I've only changed things with alfaobd, so not sure what all I can see with it on that subject.