Mr12Volt P2000 - Carplay/Android Auto w/M.O.S.T *New Model Update*

Thumbie wrote

Here is the wiring diagram for mr12volt. All the wires should be labeled from the mr12volt unit.

Also this is how to connect the camera. Photo not mine, from 20 pages back. You need to run the long cable it comes with through the rubber boot in the trunk, all the way to the front of the car where the mr12volt unit is.

Is your car a manual transmission? If so, there is an extra step. The wire labeled reverse light 12V needs to be connected to the reverse light positive.

I forget what I did now, but I want to say i used the red wire (in the trunk lid) and did a three way connection to the red wire, to the camera, and the positive reverse light wire (but don't quote me on this). I wish I took a picture.

But if you have DCT I think you just connect the red wire to the camera (in the trunk) and the Rear Cam 12v from the unit.

The red wire within the video lead is not meant for power, it is a trigger wire for systems that use it. If you're going to use the Mr12volt output camera power then running an individual lead would be required, that black wire from the camera is the negative that needs a ground connection.
Personally using a camera filter attached to the reverse light is the way to go, I've done this on many an occasion for customers and it's worked perfectly.

DavesZed wrote

Thanks for that info, my box (version 2, black box) is currently bricked, just sticks on the boot screen following the first part of the new update, wont go any further. Although I've contacted Mr12volt, they are very slow in responding and we're not getting anywhere, so I'll give this a try and see what happens

Have you tried a different USB stick? None of my newer ones worked even after formatting. I keep a 15+ year old 8gb stick for things like this.

I have the newer OEM mic support mr12volt. My issue was related to removing the USB stick too early during the update process. If your mr12volt bluetooth connection name is Car_Audio_034 or Car_Audio the iPhone 17 update did not complete. It needs to say Mr12volt_bec2.

Now that the update is correct, it works better than ever.

smass wrote

Have you tried a different USB stick? None of my newer ones worked even after formatting. I keep a 15+ year old 8gb stick for things like this.

I have the newer OEM mic support mr12volt. My issue was related to removing the USB stick too early during the update process. If your mr12volt bluetooth connection name is Car_Audio_034 or Car_Audio the iPhone 17 update did not complete. It needs to say Mr12volt_bec2.

Now that the update is correct, it works better than ever.

Yeah used a 4GB stick and then a 16GB stick still didn't do anything different.
TBH I was thinking of trying a firmware update anyway and see if it helped, otherwise I'm beginning to think my box will be heading for the bin!

DavesZed wrote

Personally using a camera filter attached to the reverse light is the way to go, I've done this on many an occasion for customers and it's worked perfectly.

yes!

i didn't install a filter. it all works but i get a lot of interference on the video

Thumbie wrote

yes!

i didn't install a filter. it all works but i get a lot of interference on the video

Yeah the interference is because of the power going through the video cable.

DavesZed wrote

The red wire within the video lead is not meant for power, it is a trigger wire for systems that use it. If you're going to use the Mr12volt output camera power then running an individual lead would be required, that black wire from the camera is the negative that needs a ground connection.
Personally using a camera filter attached to the reverse light is the way to go, I've done this on many an occasion for customers and it's worked perfectly.

What do you mean by camera filter?

itrocks4u wrote

What do you mean by camera filter?

One of these...
https://amzn.eu/d/2TA3sc3

You attach it to the reverse light and ground and it smoothes the power supply and doesn't interfere with the video signal.

GORDON.M3 wrote

Anyone who needs the iOS26 iP17 fix.

Update here: https://www.mr12volt.com/pages/iphone-17-series-carplay-disconnection-fix

That worked for me. So far no disconnect with IP 17 and IOS 26.1.

For anyone using Mr12Volt with the CCC system/controller: are you able to use the scroll/spin feature to navigate or do you also have to hit up/down only with the controller? A bit of a bummer to have to navigate with that when you have a nice scroll ability and just not sure if something isn't right on my install.

Mine EXCLUSIVELY controls with scroll. Clicking up/down, etc. doesn't work. As an FYI, Android Auto can do both and controls much more efficiently.

But let's not kid ourselves, things are a little bit clunky w/out a touchscreen. That said, I love this thing and it's really improved my daily experience.

VtecforV8 wrote

Mine EXCLUSIVELY controls with scroll. Clicking up/down, etc. doesn't work. As an FYI, Android Auto can do both and controls much more efficiently.

But let's not kid ourselves, things are a little bit clunky w/out a touchscreen. That said, I love this thing and it's really improved my daily experience.

That's so weird, I would love to have that over the up and down haha. Like you said, its a tad clunky but keeping the OE screen and having CarPlay is still so worth it. I mostly set it and forget it anyway when using Maps.

I have had my Mr12volt for 4+ years now. Recently I noticed a few new features that were not there at the start. First, in the advanced settings area, there is an echo cancelation setting. That got rid of the annoying echo on phone calls. And 2nd, holding down the iDrive knob for 7 seconds now reboots the mr12volt. In the past, I have had to power cycle the unit by unplugging it.

Update on my box issue regarding the update (iPhone 17)

Basically it's bricked and looks like there is no solution to remedy this! Mr12volt haven't come up with any solution whats-so-ever, apart from using a different memory stick and reformatting etc, the sort of stuff I'd do anyway and have tried. They also haven't even bothered to open my last message to them on 1st December. To say that I'm an affiliate of theirs as well, although I wouldn't expect any better treatment anyway, and I still can't get an answer isn't good at all.
I now have no choice other than to rip it all out and chuck it in the bin as e-waste

DavesZed wrote

Update on my box issue regarding the update (iPhone 17)

Basically it's bricked and looks like there is no solution to remedy this! Mr12volt haven't come up with any solution whats-so-ever, apart from using a different memory stick and reformatting etc, the sort of stuff I'd do anyway and have tried. They also haven't even bothered to open my last message to them on 1st December. To say that I'm an affiliate of theirs as well, although I wouldn't expect any better treatment anyway, and I still can't get an answer isn't good at all.
I now have no choice other than to rip it all out and chuck it in the bin as e-waste

I was able to unbrick mine using the micro SD update method. I think I used 3.5 rather than the current 3.7. Just rebooting with the SD card inserted allowed the mr12volt to boot up so I could complete the iPhone 17 USB update. In my case, I was removing the USB too early. It reboots twice during the update process.

Have the new mr12volt, and been struggling to get this working on and off for afew months… have some time to try again and have had no luck getting it working…

I have a 2009 335i, CIC, no factory cd changer, has the usb in arm rest next to the aux input.

I have checked the connections about 20 times, I see a red light from the FO cable, which i plug into the cars MOST green cables. The other 2 FO ends, one plugged into mr12volt, and the other end is plugged into the harness which is connected to the cic. The rest of the cables are secure and the red light is coming on mr12volt.

I did break out bimmercoding and followed the instructions…

Headunit -> Expert Mode -> 3000 HMI
Find CDMM_CHANGER_3 option and change it to mp3_cdc
CODE -> START CODING

Which got the cic to show 6 discs, which are greyed out and showing unchecked…


The radio and cd player work with no issues as well..

At this point I am at a loss. The information in this thread and other places really hasn't been helpful on what exactly to do here and seems other people have had similar experience, some seemed it was a bad FO loop but I have checked the connections over and over…


I still cannot get this damn thing to work. I gave up wtih ncs expert and inpa due to a time crunch (bad install i am thinking) and got bimmercoding and flipped the change_com3 to mp3 and its still not working....

I have seen some people also mention recoding a VO order for the cd changer but nothing explaining but casually mentions…

The last issue is since I have hooked it up my CIC when I start my car is giving me a “High battery charge” message, my usb drive is not being read by my head unit, and on my Aux port I can click into it but I cannot turn the volume up or down.

Right now I am going to reinstall INPA and ISTA+ and look for any MOST issues but was wondering if anyone else might have some suggestions…

Skylinemotorsports wrote

Have the new mr12volt, and been struggling to get this working on and off for afew months… have some time to try again and have had no luck getting it working…

I have a 2009 335i, CIC, no factory cd changer, has the usb in arm rest next to the aux input.

I have checked the connections about 20 times, I see a red light from the FO cable, which i plug into the cars MOST green cables. The other 2 FO ends, one plugged into mr12volt, and the other end is plugged into the harness which is connected to the cic. The rest of the cables are secure and the red light is coming on mr12volt.

I did break out bimmercoding and followed the instructions…

Headunit -> Expert Mode -> 3000 HMI
Find CDMM_CHANGER_3 option and change it to mp3_cdc
CODE -> START CODING

Which got the cic to show 6 discs, which are greyed out and showing unchecked…


The radio and cd player work with no issues as well..

At this point I am at a loss. The information in this thread and other places really hasn't been helpful on what exactly to do here and seems other people have had similar experience, some seemed it was a bad FO loop but I have checked the connections over and over…


I still cannot get this damn thing to work. I gave up wtih ncs expert and inpa due to a time crunch (bad install i am thinking) and got bimmercoding and flipped the change_com3 to mp3 and its still not working....

I have seen some people also mention recoding a VO order for the cd changer but nothing explaining but casually mentions…

The last issue is since I have hooked it up my CIC when I start my car is giving me a “High battery charge” message, my usb drive is not being read by my head unit, and on my Aux port I can click into it but I cannot turn the volume up or down.

Right now I am going to reinstall INPA and ISTA+ and look for any MOST issues but was wondering if anyone else might have some suggestions…

Firstly did you code $672 to your VO? If you're not sure then simply go to your CD option and if you have multiple CD's available then it's set correctly, if only one CD then it isn't.

Also your MOST line isn't connected correctly, evident by your USB and AUX not working, as these come via the MOST line.

I have a video for the boxes that runs through the coding and connection, although it's on my Z4, it's the same principle. Hope this helps...

DavesZed wrote

Firstly did you code $672 to your VO? If you're not sure then simply go to your CD option and if you have multiple CD's available then it's set correctly, if only one CD then it isn't.

Also your MOST line isn't connected correctly, evident by your USB and AUX not working, as these come via the MOST line.

I have a video for the boxes that runs through the coding and connection, although it's on my Z4, it's the same principle. Hope this helps...

I just finished everything off, thanks for the advice!! I tracked down the most issue to the test port under the driver footwell. Plugged that in and everything became green in ista..

Next I added 672 to cas and nfrm, wrote them then pushed them to the cic, plugged everything back in and it came on!!

I did confirm thay cmm_change3 was set to mp3, writting the cic did this so I didnt have to edit anything after the VO changes.

Cheers for the help!

Skylinemotorsports wrote

I just finished everything off, thanks for the advice!! I tracked down the most issue to the test port under the driver footwell. Plugged that in and everything became green in ista..

Next I added 672 to cas and nfrm, wrote them then pushed them to the cic, plugged everything back in and it came on!!

I did confirm thay cmm_change3 was set to mp3, writting the cic did this so I didnt have to edit anything after the VO changes.

Cheers for the help!

No problem, glad you've sorted it

Blows my mind how many of these cars have open most loops. How were they working in the first place?

Hi everyone - I've got an E60 with CCC and was planning on getting a MR12VOLT however I've seen some videos showing Carplay/Android Auto being stretched out - almost as if the aspect ratio is wrong. Is this still an issue or was it fixed?

I've trawled through most of this thread and couldn't find anything

Installation report:

2009 M3 without CDC changer. CDMM_CHANGER_3 was set to kein_cdc. I saw on reddit that someone had pre-emptively changed it to mp3_cdc and ended up having to change it back to get it to work, so I left it as is. It didn't work the first time, but I was able to code mp3_cdc even with the Mr12Volt installed. (I had heard that might not be possible with it installed, so I left everything out loose until I got it working.) Maybe there's a new version that allows coding after the fact.

I'm trying to figure out where to put the box itself. In many install videos, it's tucked up from under the glovebox area. I see where that space is, but there's some sort of heater motor actuator in the way that prevents me from sliding it up smoothly:



I could jam the unit past this, but I'm concerned about the pressure it puts on the case of the Mr12Volt. I also don't want to unscrew the module because I assume there's an actuator that feeds inside the heater box.

Anyone run into this issue? I wonder if newer versions of the module come with a case that's slightly bigger. I'll mess around with it. [EDIT] That was easy. It fits a little further back. Now I just need to add a little foam tape so it doesn't rattle around everywhere, but not so much that it impacts airflow to the unit.

One issue I noticed a few times now is that if I start in CarPlay, I don't get audio until I switch to the radio and back. I'm not sure what the trigger is for that state.

I noticed that my phone will start up CarPlay without the car being turned on. Is the Mr12Volt listening over Bluetooth the entire time? Has anyone noticed an impact on the car's battery with this? Maybe it's negligible.

I'll try disabling the "auto-answer" options in the Bluetooth menu to see if that helps.

This might be a known thing. I haven't seen it mentioned in the forum posts I've read.

[EDIT] Found the posts. Sounds like it turns on automatically when unlocking the doors. The car eventually goes to sleep as normal since the start button turns off after a while. I think this car drains the battery faster than I expect. While installing the unit, I turned the car off and on multiple times. Afterwards I put it on a trickle charger for 18 hours and it still wasn't done. Tonight I was messing around with it in accessory mode for about an hour and now I get the battery light again. I'll charge it up and stop screwing with it.