Repair-It

Ended up sort of impulse buying a CarPlay/Android Auto module for the S550.

https://www.aliexpress.us/item/32568071 ... ry_from%3A

Manual attached.

Many or most of these seem to use the same module so paying extra doesn't really do anything except add middlemen. You can pay up to $400+ for the same thing in various places including eBay.

The installation looks pretty easy, especially compared to the Malibu.
https://youtu.be/gpwKuAQ6p74?si=1YJtcfF851RMu39e

I also used a coupon so I got it for $152.06 shipped which is, again, really cheap. It does NOT come with the microphone splitter cable that would tap into the overhead console mic and let the system use that. It does come with an external mic that I'll have to affix to the overhead area which annoys me but if I want a kit with this splitter, I'd have to pay considerably more and I'd rather attempt to track down the cable or live without it.

For example, for $450, I can get a kit that comes with a mic splitter. https://www.mr12volt.com/collections/ca ... 00-ntg30mm

I don't think I want to pay $350 for a cable. In fact, I know I don't.

Received. I may need to wait until late August to install due to some factors.

I really dragged my feet on this because these add on modules have been available for over 5 years. There are at least two ways to add this functionality to a car: 1) replace the entire system/screen. There are extra wide screen options that resemble the W222 I think but I think the total cost is high and I guess I don't like the idea of ripping out the factory screen and jamming some other thing in there. No idea what happens to COMAND which does display certain HVAC, seat control and vehicle features. 2) add on module that uses the factory display and all buttons. You can switch between COMAND and the add on module.

I elected for #2. Cars with no nav system really have to pick #1.

This whole experience was very much like doing car audio so anyone familiar with various plugs and having to physically mount a new module somewhere will immediately be at home for this installation.

There were a few videos I used and also the instructions.
https://youtu.be/9ryB0uldeLw?si=EfspvNtZQX5uU51b
https://youtu.be/vLGB5XWdj64?si=BYuRvie9huk-f3NK

Step 1: remove the fascia panel under the COMAND module (normies would know it as "the CD changer" but it's actually the entire brain of the COMAND system that drives the screen and stuff, with the hard drive and all that stuff). Then remove the surround/door. 4 screws. The upper screws are behind these tiny hinged doors that pivot out of the way. So fancy.

At this point I thought the COMAND unit would just pull out. Not so fast. Something was hanging it up. I pulled harder. No joy. Giggety. I decided that because one of the videos showed the HVAC/clock/vents (which is also a module) removed, and that would let me see more of what was going on, I removed that next. I have removed this before so that was handy. Unsnap the upper cover that runs under the instrument cluster and nav screen. Remove one screw at the center. Snap off the covers at opposite ends of the dash (pass side covers a fuse box). This reveals one screw on either end. Remove them. Then the whole panel snaps off. This unit felt so substantial and high quality, FWIW. Nothing broke.

With this panel out of the way, I could see that there was some mystery module hanging up the COMAND unit from pulling out. I unstuck it and took a look. One end had a small version of an ECM style plug (swinging lock arm). The other end had....CAT5? WTF is this? I tried copilot which was somewhat helpful. But the real answer came when I realized the CAT5 went into the glove compartment to the iPod adapter. So that's what this was. The original owner paid $900 to add this if I recall. Anyway, I unstuck it and now the COMAND unit pulled out easily. Took about 30 minutes to get to this point and had I not struggled with the iPod module I could have done it faster. Actually that pic is cheating - I had already wired up the Android Auto/Carplay module. Looks like that took me around 20 minutes to sort out all the harnesses and plugs.

So here is the first test. It worked immediately EXCEPT I had no audio. I tried some things and then realized I installed the fiber plug into the wrong socket. You unplug the COMAND, unclip the fiber plug, plug in the new harness to the COMAND that goes to the unit, and insert the fiber plug into that one (back into COMAND). Once I realized my error, audio worked. Operation was confirmed though I did note some things after testing stuff. Kind of a to do list.

1) My plan was to wire into the factory mic or otherwise route the cable and stick the aftermarket one somewhere minimally ugly.
2) Pressing the steering wheel voice command button (Mercedes called it Linguatronic, since 1996) did activate the Google assistant which is great. But it also activated the factory assistant. That's not great. Google could hear me but then the car was being annoying. Need to see if I (or the BenzNinja) can code out Linguatronic but have the button still respond for Android Auto. I think this is possible. Workaround: turn on Hey Google which does work but I guess I don't want that on. Workaround 2: just select the microphone on the screen but since this isn't touch it requires some knob twirling so it's a bit annoying.
3) USB seems to be slow charging only. I was worried about this but I figured by 2025 even a Chinese unit like this would have sufficient charging current for modern devices. I guess not, unless there is a secret setting that I couldn't find. As a result charging could not keep up. I could test it on a longer drive but I think my phone would slowly drain which is bad. Workaround: use the charger I had before and just use wireless Android Auto. I tested this and it worked fine but I like the plug because when you unplug it turns off Android Auto on my phone (and pauses music). Because this is aftermarket, when in wireless, my phone stays connected for a minute or so even continuing to play music. This annoys me but I can disable Android Auto via the notification menu or just walk away from the car. I may be able to wire in high current charging via a dongle but pass data through. I'll look into this. I guess the most industry standard solution would be to install a small USB hub and power it from my regular charger, then hook my phone to the hub which should pass data to the Android Auto box. I'll see if I can find a small one that has at least 2.4A charging.
4) Clean up install and figure out a permanent place to mount the box.
5) A test call with Ian revealed some echo on his end (he could hear his voice). He later said it wasn't super loud but this is not ideal. Something to look into.

After lunch and my walk I resumed the installation.

I ran the mic up the B pillar and along the headliner to the overhead console area. This took a while just to figure out the right crevices but wasn't hard.

Then I tried to nestle the unit under COMAND. It actually fit but then after half reinstalling everything I realized the ashtray door would only open halfway. It wasn't quite enough for my charger in the 12V socket plus this seemed ghetto and would bother me long term. So I took everything apart and looked again.

Next option was kind of in the dash between COMAND and the glove compartment. The unit did fit but it was clearly just going to rattle around in there and that would also be unsatisfactory.

Finally I realized I may have to do something in the passenger footwell. I removed some more panels to gain more access and began working on passing all the needed wiring through the small access to get through to the footwell. It was tight. Also the harness wasn't that long so I had to now reinstall COMAND for hopefully the last time, verify ashtray operation, and pull every bit of harness into the footwell. This took a while.

Once COMAND was installed, I decided on a place for the unit. I pulled up the floormat, carpet and side carpet a bit. I kind of jammed the box on the left upper side of the pass footwell. You can see a small lump under there but it's not too bad I guess. It was big enough, however, that I was unable to reinstall the access cover for the cabin air filters. I ended up trimming an inch off the plastic. I could have done a higher precision job but you don't see it.

I did have one scare: the hazards didn't work. I randomly decided to test them since I was thinking the unit like intercepts the CAN signals and stuff. But they didn't work! Did a little research and no one else had this issue. But I did find someone who had a hazard lights issue in general and one person in the thread mentioned that the control for the hazards is actually in the HVAC control module, which was sitting in my back seat, unplugged. Whew!!

Then I reinstalled everything else: HVAC panel and screws, side covers, vent fascia below the nav screen, COMAND door and lower trim cover. This took me until like 6 pm by the time everything was buttoned up. It was straight up car audio type of fiddling.

And yes, the hazards worked after I plugged the HVAC panel back in.

Some operational shots. Deeper in the menus I found this: I performed the procedure (which played some loud noises) and will test it tomorrow. It is measuring the audio delay and I guess this has a bearing on echo cancelation. I don't know if it's going to be full duplex or just sort of mute my mic while the other person is talking. Hopefully it's good enough for calls, which is its purpose. I stuck the mic above the rearview mirror and if that bugs me I can always drop the upper console and splice into my factory mic wire per the instructions (and switch the settings to OEM mic).

Overall this was a really nice kit for $150. And the electronic integration works as promised. You hold down hang up on the steering wheel to manually switch to the system. The COMAND knob controls Android Auto in non-touch fashion. The back button does something. The nav/phone button seems to bring up the app menu. Adjusting the HVAC does not bring up any overlay so I have to switch back to the COMAND if I want to see stuff. But since I have hard buttons I can adjust it and I leave it at 71F 100% of the time anyway.

Really just a lot of car audio installation type fun to get everything physically integrated. Nothing crazy, just time consuming.

Oh and audio quality seems good. It has a lot of configuration options where I can raise the system volume if the gain is wrong as well as a 3 band EQ. I will test more but so far so good. I think the audio is done over bluetooth. It is the screen projection that is either plug in or wireless. It does also have a screen mirroring function. I think I could play Youtube videos on it and stuff.

Apparently there is a USB standard for my issue called OTG (On the go). There are Y cables (or hub looking things that do the same thing) that take power input to charge the host while allowing a data connection via another USB port. A common use case that everyone understands is you want to charge your phone but also connect a flash drive to your phone. So the device passes power from one port to your phone while passing data via the other port.

This is what I need EXCEPT people have already complained via reviews that they didn't work for Android Auto (I guess I'm not the only one).

EDIT: Ah crap. These are designed for when the phone is the host. But in this case, the Android Auto module is the most. It won't work backwards.

EDIT 2: Engineers to the rescue!!! https://www.tindie.com/products/rkoripa ... e-carplay/

But it hasn't shipped since 2023......SIGH.

The "good" news is, this is an issue on cars with factory Android Auto. I did e-mail ZTUZAUTO just to see what happens. The interaction with the sales team (via Ali Express) was a good effort but they were not technical support.

kevm14 wrote: Sat Aug 23, 2025 7:09 pm 1) replace the entire system/screen. There are extra wide screen options that resemble the W222 I think but I think the total cost is high and I guess I don't like the idea of ripping out the factory screen and jamming some other thing in there. No idea what happens to COMAND which does display certain HVAC, seat control and vehicle features.

Right, conveniently I just found this video that shows how to install such a system: https://www.youtube.com/watch?v=VbW9MhP134w

This video also does a more complete job showing the required dash disassembly (except for the extra part pertaining to removing and replacing the LCD which I did not touch on mine).

There are probably a few variations of these by now but the gist appears to be an Android-based extra wide touchscreen. It seems to completely do away with the COMAND interface (except maybe the backup camera that it seems to pass through - and my car doesn't have that). It even duplicates the missing physical controls with touch controls in the same general area and order of factory. Impressive. It isn't going to be an OEM-grade screen but is an interesting option I guess. A little too aftermarket for me but you could argue this is a superior experience to what I did since you get touch and still retain the COMAND knob if you want to use it. I do think these are more expensive but still very affordable. $400 range comes to mind but too lazy to check.

Ok I checked. Here is the first one I found. https://www.aliexpress.us/item/32568078 ... 05837325_1

This one claims you can still switch back to the NTG interface though it shows the wrong one for a W221.

I will also say this COULD actually be an easier install since the module and screen is a single unit. I wouldn't have had to spend all that time hiding the module.

Here is another one (12.3") which is even wider and replaces the cluster bezel, too: https://youtu.be/VZkWTw316Zo?si=dWjPlZwUmGYwGO-k

The bezel looks kinda bad but this sort of matches the W222 look. Eh, I like the factory look.

I can reverse my install someday if I keep the car long enough and decide that I really need touch. I won't know until I put some time on the system I just installed. If the module failed for example, I guess I'd revisit what to do. Getting widescreen Carplay/Android Auto with touch would catapult the car at least 10 years forward and in most cases more like 15+ based on OEM adoption for widescreen Carplay/Android Auto.

Enlisted the BenzNinja this morning to help disable the Linguatronic. I assumed the position - 20A charger, laptop connected, ignition on, and screenshot the Ultraviewer password so he can log in when ready. But it didn't go as planned. He tried some stuff and asked me to test. Still worked when I pressed the voice command button. He did some research and seemed to be sending me down a more conventional path though I didn't fully understand at the time. He wanted me to pull the fuse for the Linguatronic module. 5A, in the rear SAM, accessible through the middle seat arm rest. That was fine except it was one of those locking ones and when it finally came out, it slipped out of my needle nose and fell into the rear SAM abyss. This did disable the Linguatronic but it also disabled....all audio. Actually it was worse, it would not even play the CD (I wanted to rule out variables and I guess I trust the CD player). He said, right, so I'll have to unplug the Linguatronic (or leave the fuse out I guess), unclip the fiber optic harness from the plug, and loop them together. The module requires power to pass on the fiber signal though I don't know how it works internally.

Anyway, I had my trunk taken apart and didn't really have anything good to show for it. He did claim he coded out the Linguatronic so I shouldn't set codes for it missing.

I ordered a MOST fiber loop adapter from Amazon which is good to have on hand anyway.
https://www.amazon.com/dp/B01M5IYTD9?re ... asin_title

But I still couldn't wait. So I poked through the COMAND coding in DAS and did see something called VCS, or Voice Control System. I figured this was Linguatronic but it was marked as Present, which surely isn't a reliable way to disable it. I shut the laptop down and fired up my trusty Launch x431 Benz Elite, entered the COMAND module and coded VCS to Not present. Then I made sure the module was fully plugged in (including the fiber), plus the fuse (I used a spare 5A from the glove compartment, I think OEM spares), and tried everything. The result?

It works!! Linguatronic is in fact disabled AND the button still commands the Google voice assistant in Android Auto. Oh, and the sound works again. Hooray!

I sent a message to the BenzNinja and he said he tried to code VCS off but was unable to do so. I told him I used a Launch. I'm sure his facial reaction was interesting.

So I put the trunk stuff all back together and consider that problem solved.

Later, I received my little charging pass through thing and tried that. It isn't fast charging but the phone no longer says Slow charging. Seems like an improvement though maybe someday I can find an adapter like this that runs on USB C PD (power delivery) and keep up with the phone no matter what happens. And frankly there are a million scenarios where you'd really like your phone to charge as quickly as possible when you get in your car.

Overall I think I've tackled the outstanding integration issues so presuming this thing actually continues to work, I think I will be happy with it. I'm a little annoyed that I never read about this but I bet 99.9% of people who retrofit this type of thing to an old car would either not even think to press the voice command button (though it works in newer cars which is why I was kind of obsessed with it), or press it once, hear the factory system and go "oh, I can't use that" and move on. Not me. I'll be sure to pass this gem of knowledge on.

After plugging in that dongle I wasn't satisfied that the USB plug had such little slack. The wire was also bound up so I removed the fascia, loosened COMAND and pulled another inch or two of USB wire through. That's better.

Battery ran down 3% during my 30 minute commute. So the charging situation is not solved. The company told me the USB interface isn't designed for charging. So my options are find a better dongle than what I found on Amazon (may be tricky - and it did improve the situation), live with a slight discharge or switch back to wireless and use my normal car charger. All have pros and cons. My preference is to find a better charging dongle (perhaps USB C PD) and stick with the wired setup.

kevm14 wrote: Sat Aug 23, 2025 7:12 pm Oh and audio quality seems good. It has a lot of configuration options where I can raise the system volume if the gain is wrong as well as a 3 band EQ. I will test more but so far so good. I think the audio is done over bluetooth. It is the screen projection that is either plug in or wireless. It does also have a screen mirroring function. I think I could play Youtube videos on it and stuff.

I can force audio over USB by disabling the audio part of the Bluetooth connection. Then only calls are via BT. It will still probably require me to switch to handset if I am on a call and exit the vehicle but I think even factory systems can be a little clunky here. So I don't feel too bad. I do want to try a call to test the echo.

Yesterday while reversing I noticed that the system immediately kicked back to COMAND. It detected I selected reverse. But I don't have a camera so this is undesired. So I went into the settings. There was no option to disable the camera but I noticed it was set to "CAN" meaning it picked up that I was in reverse from the network. Cool.

Another available setting was 12V, since it has a discrete signal wire for like an aftermarket reverse camera or something. I am not using that either so I set it to 12V knowing it should never detect anything. Problem solved.