How to add a good Alpine 6 CD changer to your Becker 1432 without rewiring ANYTHING

[Dbreid]

All,
This one took me a long, long time to research, so I figured I'd try to help folks out by writing out my story.

What I started with -----------

I have a 1992 500e. That means it came with a "multi piece" system called the Becker 1432. It is easy to google for pictures of that deck, but this is the system used in all 1992 and 1993 (pre-facelift) Mercedes e-class 500e's. In 1994 they swapped to the Becker 1492 unit, which was much better. If you have a 1492, stop reading this post, because there are tons of options for you.

However, if you, like me, have a Becker 1432, you know a few things...
1.) It usually sounds like hell.
2.) If it has a CD changer, it has a Becker 980. This is a 10CD setup, and is a nightmare. Mine worked when I got the car, but never very well. After a while, it decided to stop working. I went so far as to take it apart and figure it out (turns out that the culprit is a bad plastic gear design, which makes all sorts of problems, and isn't really fixable.

Anyway, most people (including Becker) will tell you some variation of the following:

"Who uses CD anyways?"
"I like to listen to the engine!"
"I use a FM modulator for either an iPod or a changer"
"Trash all that Mercedes junk, and put in some rad ICE!"
"Skip the changer, and send the head unit in to Becker and they'll install a AUX input, and then just hook your ipod up, and you are set!"

Well, I didn't really like any of those answers much. But I had bad FM reception, and was running out of working cassettes from the 80's.

So first, I decided to send my head unit in to Becker for servicing, and adding an AUX.

How to Send in your Head Unit to Becker-----

Firstly, go to this website:

http://www.beckerautosound.com/1432-1991/index_300CE_E.html

That's the Becker site. And yes, it looks like the type of site that you have your 9 year old son design the first time he has seen HTML. Terrible.

But I digress.

Basically, you take the headunit out of the car, and in my case, I took the FM tuner out of the trunk as well.

You box them up, and send them to Becker (no need to call in advance... which is weird), and include a note in the box that says what you want done, and a phone number and address for you.

They will call you with an estimate, and then after a while, call you back and tell you it is done, and extract payment from you.

In my case (I had the Headunit serviced, an AUX input added, and had the FM tuner rebuilt) it was a little less than 400 bucks.

Fair enough. The folks at Becker were really nice, by the way, when I talked to them on the phone.

That worked really well for me. I enjoy my iPhone tunes in the car, and it works very well. I wired the whole thing into my center rolltop, and it works great.

But still... the CD player.... Grrrr...




What DOES NOT work for the CD player (Becker 980)---------

In my quest to get that thing working, I tried a few things:

1.) Buy more of them...

I bought two other Becker 980 units on eBay. One of them was advertised as working, but was jacked up (there were broken gear parts in the box) when it arrived... (I got a refund, and the guys was cool, btw). The other I bought as a spare, thinking I could make one good one out of two... A few hours messing with it, and I determined that without access to new (not brittle) white plastic gears there was no way I was fixing it...

2.) I called Becker. They said that they USED to fix those things, but the guy said they basically refuse to fix them now. He said that the 980 was a total POS even when new, and it skipped so much when new, they couldn't run them in the SL cars (more on this later!). He said they used to rebuild them, but they only did it in the winter when they were bored, and they charged a ton for it, because it was a terrible job, and about half the time, they broke again shipping things back to the customer.... Grrrrr..

3.) I did a bunch of reading, thinking there might have been a later version of the 980...

I found this:

http://www.mercedeslist.com/2630.html

I thought HA! The Becker 2630! That will work! So I waited, and found one (new in the box) on eBay. It does indeed have the same 10 disc cassette, but it does NOT work in our cars. At all.... It is a completely different setup, and there is no way it will work...

Sigh... So eliminate that stuff.

What works, and what you need--------------

In reading, and looking through wiring diagrams, I noticed that the R129 chassis seemed to have some other type of CD changer, and in order to make it work, they ran a thing called an MX3192.

It is basically a little box that has a few inputs, and some weird wiring sticking out of it...

Looks like this (In this picture it is sitting on top of the CD changer):


So you need to find one of those.

And then you need to find an Alpine CHM-S620. This was a LOT easier to find, and they are all over eBay. I bought one new in box (or maybe used in box, but it had all the parts... so here are some pictures with bar codes to help)













Note that it just has ONE input and output... See the cable sticking out below:





So basically, to get this to work, you unplug the Becker 980, and insert the connections as follows (It is hard to describe in words, so I diagrammed some pictures):









See next post, as this one is getting loooong

 

[Dbreid]

So with it wired as above, it works PERFECTLY!

When you power up the system, it will check all the CD's and the displays work properly in the Dash.
You can change between CD's with the Becker 1432 correctly, and track forward and back between tracks (it is actually really fast, as well!)
The sound is great!


Now, I needed to hang all that stuff up under the rear deck lid, and I didn't want to drill new holes. So I used the 4 factory mounting bracket bolts for the 980, and made an "adapter" plate out of ABS plastic. I made it from plastic, because I wanted a little flex when installing it, so it wrapped around the rear deck well, and "pressed" against it to keep vibrations to a minimum.

I used Velcro as a further damper.

See my install below:





And here it is installed:




Hope this helps folks!!!

-Dan

 

[Dbreid]

One more thing... In the last picture above, I left out the inner trunk carpet liner, so you can see the Factory Becker 1432 Amp and FM tuner locations as they relate to the CD changer.

 

[alexis]

Hi,
I have had the Becker 1492 and the Alpine CHM-S620 in my 1994 car for about ten years now.
Both work very well together and the Apline is very stable even on rough roads.
Good choice
Alex

 

[dullfig]

Hello all! new to the forum.

I have a 560SEL (1991) and am wondering if this information applies to that model also. There's a guy selling a becker 2630 cd changer with harness, and he says it came out of a 560sel. Is that possible?

thanks to all

 

[Dbreid]

I suppose anything is possible. If you want a brand new in the box 2630 lemme know, as I am not using the one I have and if you think it might work, I'll sell it.

 

[Ingvar]

I just wanted to say thank you to Dbreid for this very useful thread. I decided to try this out and purchased a MX3192 on Ebay. The amplifier/ converter came mounted on a Mercedes CD changer MC3191. While waiting for an also Ebay purchased NOS Alpine CHM-S620 I decided to mount the MX3192/MC3191 combo in my -92 500E. Removed the non working Becker 980 and installed the "new" unit. Installation was very easy, even the power connector matched. Story short; it worked! And the sound from the original untouched sound system was very good, at least to my (aging) ears ..

 

[Jlaa]

Thanks for this super useful post. Now I will try to find a Mx3192 / q6820135 / 002 820 3289.

I do note on ebay that the MC3191 changers for sale are stripped of the MX3192! Argh.

 

[Jlaa]

I was able to accomplish the same thing, except instead of using an Alpine MBUS CD Changer, I used an Alpine MBUS emulator.
The net effect is --- I got bluetooth on the Becker 1432 with exceptional sound quality without rewiring anything!

I bought this emulator:

YATOUR USB SD AUX iPod/iPhone Car Music interface for Alpine M-Bus plug
http://www.ebay.com/itm/121375203352

Yatour Bluetooth Adapter For Yatour M05 M06 M07 Items /Hands Free Calling
http://www.ebay.com/itm/252648604774


This emulates an Alpine MBUS Changer. The benefit then is that this device provides Bluetooth, SD card, 1/8 aux in, and iPod input --- all into "CD Changer" input of the Becker 1432 --- for the cleanest sound. However, I am only using the emulator for the Bluetooth functions. I tested the other functions and they work well, but I am not using those function and will hide this emulator in the rear trunk behind the molded carpet, next to the Becker receiver.

Proof of working --- https://youtu.be/fxe6mRqTJS0

Instructions Below -

 

[Glen]

This is great news. It looks like they have a version for the Becker/Porsche HU's too. I have a CDR-210 in my silver car and with this I can add a BT interface.

 

[Jlaa]

Indeed, I have used a yatour with both a c(d)r-210 and 220 for several years with good results. For the w124 with the BE1432, though, the yatour does not work natively. If you want to keep the orig head unit to preserve the look, then you must get the mx3192 translator to use a yatour. That was hard to find .... I bought one at a real live non-ebay auction for $20. Actually I had to buy a lot of two, but one of them was broken and didnt work.

 

[Rouven036]

Excellent info,thx! Unfortunately skipped my original sound system with all wiring and components to a newer becker aps30 and 6 channel amplifier years ago. But will install this on the sl with the 1430 setup. Also have a mx3192 already.

 

[makemann]

Jlaa, do you disconnect the CD player completely from the tuner?

To clarify, you use Bluetooth just to stream music, and not to place hands free calls?

Thanks!


Sent from my iPhone using Tapatalk

 

[Jlaa]

Hi M - my car did not come with a CD changer, so yes, one would disconnect the existing CD changer. The yatour comes with a mic that you can wire into the interior in the car so that you can make bluetooth calls, but I decided not to hook it up right now because -

1) In order to hear anything from a bluetooth call one would have to turn the stereo on
2) I may eventually hook up the mic but I dont like the aftermarket look of the supplied mic. I may eventually try to wire in the mic for the existing non-functional analog cell phone into the yatour ... thus keeping everything discreet. I think the connection to the analog phone control panel, which is next to the dome light, is RJ11 or RJ45 based so it would just be a matter of finding out the pinouts to the control panel (where the orig mic is mounted).

 

[makemann]

Thanks J! Using the existing mic idea is brilliant! Unfortunately, way beyond my abilities. Once I get the interior finished on my other project, I'll tackle this.

 

[darek_u]

Reviving this old but extremely useful thread. I recently purchased the nice combo of MX3192 and MC3196NA CD changer with all the peripherals - mounting bracket, harnesses, grey case etc. I hooked everything up just to try how it work - no joy! My Becker Mexico BE1460 (Euro version with RDS) doesn't see the CD... Not at all. I checked the wiring and power 10x times - it is 100% correct. Changer as such works - I can remove the CD magazine but it is not visible for the radio.Question - will MC3196NA work with my Becker? Does the radio unit need some kind of set up/activation to see the changer? I don't believe it, it's just simple old fashion ICE stuff but I prefer to ask first.
I think there are 2 options here:
1. CD or interface MX3192 is faulty (seller guaranteed it working)
2. MC3196NA does not work with BE1460 and I need to purchase Alpine CD.
Looking for some advice here...

 

[Jlaa]

Hmmmmm ..... if you go back to the simplest configuration, does the Becker 1460 head unit recognize the original 980 CD changer? Even if the transport mechanism is broken (they all are) --- does it recognize the 980?

If yes, then start adding complexity with the MX3192, Alpine Changer, etc ?
Also I read somewhere on the web that the MX3192 has a fuse inside and someone mentioned that the fuse occasionally blows. I haven't needed to open mine up ---- maybe try that?

 

[darek_u]

I don't have the BE980 to compare - that's why I decided to purchase MX3192. Becker changers are hard to come by and not very reliable... I opened the interface but I can't see the fuse. On the other hand it is pretty packed inside, all I can see is printed board with SMD components. I may go little deeper if needs be.

 

[Jlaa]

Reviving this old but extremely useful thread. I recently purchased the nice combo of MX3192 and MC3196NA CD changer with all the peripherals - mounting bracket, harnesses, grey case etc. I hooked everything up just to try how it work - no joy! My Becker Mexico BE1460 (Euro version with RDS) doesn't see the CD... Not at all. I checked the wiring and power 10x times - it is 100% correct. .

Dumb question ---- did you try unplugging the battery to the car, unplugging all the cables, and replugging in all the cables, and see if that works?
I know it seems obvious but I upon further reflection, when I used the MX3192 with the yatour that I had some finicky stuff where the BE1432 wouldn't recognize anything unless I unplugged the battery and "finagled" all the cables. I must have unplugged the car battery about 10x that day.

Recall that the radio still is powered by the car even if the ignition is shut off --- power is disconnected only if the battery is unplugged.

 

[darek_u]

I didn't disconnect the battery however the power to the amplifier/tuner part in the trunk was unplugged several times. I'll try tomorrow this trick.

 

[darek_u]

I tried with battery disconnected - set up everything when battery is off and then reconnect - nothing... Becker doesn't see the CD changer. Bad MX3192 or non-compatible CD changer?

 

[Jlaa]

I am sorry, I dont know how to troubleshoot this other than to try swapping individual components at a time ..... and part of the reason is bc I do not know if the BE1460 is capable of using a BE980 to begin with..... which is what the mx3192 is designed to build upon w additional functionality (let HUs which are used to driving Sony-sourced BE980s also drive Alpine-sourced changers).

Perhaps you you could contact Becker and ask ....

or Perhaps you could source a broken BE980 (for free?) and see if the BE1460 recognizes the electronics (knowing that the mechanical portion would be broken) .... if the bus communicates, then you can guess that the MX3192/alpine combo should work in theory...

And then the next cheapest thing to do might be to source a cheap used Alpine changer ... and if that doesnt work then probably the mx3192 is broken .... the mx3192 being the most expensive and least available part of the whole equation....

 

[darek_u]

I've been away for business trip with limited time for reply - sorry. BE1460 is definitely capable of using CD changer. Model 980 is straight plug and play without any interface. For other non-fiber changers MX3192 is required. I did some digging and MC3196NA is non-fiber data transfer CD changer for 1996 - 1999 MB cars. It should work with older radios via interface but it looks like it may not... Pity because the one I have is literally new like looking super clean unit... Anyway, the plan is to check thoroughly MX3192 and then probably buy Alpine CD changer. These are cheap and easy to find, I just hate the fact that I'll have the nice piece of equipment that will collect the dust on the shelf... Oh well, such is life.

 

[sPoTwArEz]

Thanks for such helpful guides regarding the connection of the Becker 2000 series to Yatour CD Changer Interface.
I have the same setup as you in my 300SL, but I am still missing one important part:

The MBZ/E-ALP interface cable, that connect between the center DIN connector of the MX3192 and the Yatour M-Bus DIN connector, consisting of two 8-Pin DIN Females (with one +12V DC cable at its ends, to supply power to the Yatour), was originally developed to take control of the Alpine CHM-S630 CD changer.

Big problem here is that I am no able to find this cable, since it is no longer been manufactured or sold, and there is no way to find one used at the moment...).

I would be very interested to get the pinout for it, in order to make my own cable harness. Would you please help in suplying me the pinout?

Tkanks a lot
Christian, Madrid

 

[kre8tive202]

I just bought the MX-3192 and the Alpine CHM-S620 to put in my 500E in replacement of the 980. Does anyone know where I can get the wire from the 3192 to the CHM-S620 (cd changer)?

 

[LWB250]

Here's a picture of what's used for reference if you need it:

https://www.ebay.com/itm/MERCEDES-G...ash=item2cd37fcf4c:g:euEAAOSwpeFa2pf9&vxp=mtr

Looks like a pigtail of sorts with a round "Phillips" type plug on one end and a standard DIN CD connector on the other.

Dan

Dan

 

[Jlaa]

Here is a mx3192 for sale WITH the cables. Good deal. No affiliation.

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/173522039479

 

[darek_u]

This is a GREAT deal. I paid twice as much...

 

[Jlaa]

This is a GREAT deal. I paid twice as much...

Did you finally get the setup working? Last I remember you were trying to get a BE1460 with the MX3192 working with an Alpine Changer?

 

[darek_u]

Did you finally get the setup working? Last I remember you were trying to get a BE1460 with the MX3192 working with an Alpine Changer?

Not yet. I was focused on other projects but this one is not forgotten. I think this winter I'm gonna tackle it while renewing/refreshing trunk area and installing hands free system.

 

[JoeyManhattan]

I’m curious if you get it working, I just installed the full setup with a Yatour and it does not seem to work. I only get a CD “E” on the head unit. I’m wondering if this error is due to the lack of the power portion of the cable in my current setup.

 

[Jlaa]

I’m curious if you get it working, I just installed the full setup with a Yatour and it does not seem to work. I only get a CD “E” on the head unit. I’m wondering if this error is due to the lack of the power portion of the cable in my current setup.

Upon re-review of my notes --- yes --- you absolutely have to have power. See below three pictures. Sorry if I was unclear or led you astray earlier. Basically power comes from the rectangular mercedes connector at the tuner pack mounted in the upper right portion of the trunk. Your new cables should do the following:

• There should be a rectangular Y at the tuner pack That rectangular Y takes the existing power from the chassis harness and feeds one end to the tuner pack to keep the tuner pack functioning.
• The other end of the Y feeds a rectangular connector that "runs along" with the round DIN cable and goes to the MX3192.
• Once at the MX3192, the rectangle connector that is carrying the power needs to Y again.
  • One end of the Y feeds power through a rectangular connector to the MX3192
  • The other end of the Y takes power and puts it on some pins of a round DIN cable that goes to the Yatour. This is what powers the Yatour. Data+Power travel on the same round DIN cable to the Yatour.

 

[JoeyManhattan]

Upon re-review of my notes --- yes --- you absolutely have to have power. See below three pictures. Sorry if I was unclear or led you astray earlier. Basically power comes from the rectangular mercedes connector at the tuner pack mounted in the upper right portion of the trunk. Your new cables should do the following:

• There should be a rectangular Y at the tuner pack That rectangular Y takes the existing power from the chassis harness and feeds one end to the tuner pack to keep the tuner pack functioning.
• The other end of the Y feeds a rectangular connector that "runs along" with the round DIN cable and goes to the MX3192.
• Once at the MX3192, the rectangle connector that is carrying the power needs to Y again.
  • One end of the Y feeds power through a rectangular connector to the MX3192
  • The other end of the Y takes power and puts it on some pins of a round DIN cable that goes to the Yatour. This is what powers the Yatour. Data+Power travel on the same round DIN cable to the Yatour.

View attachment 90835 View attachment 90836 View attachment 90837

No worries, I need that cable...yesterday. If you have a lead on one of the cables or what pins I could solder leads to, that would be absolutely great.

 

[Jlaa]

I have the same setup as you in my 300SL, but I am still missing one important part:

The MBZ/E-ALP interface cable, that connect between the center DIN connector of the MX3192 and the Yatour M-Bus DIN connector, consisting of two 8-Pin DIN Females (with one +12V DC cable at its ends, to supply power to the Yatour), was originally developed to take control of the Alpine CHM-S630 CD changer.

Big problem here is that I am no able to find this cable, since it is no longer been manufactured or sold, and there is no way to find one used at the moment...).

I would be very interested to get the pinout for it, in order to make my own cable harness. Would you please help in suplying me the pinout?

Tkanks a lot
Christian, Madrid

I just bought the MX-3192 and the Alpine CHM-S620 to put in my 500E in replacement of the 980. Does anyone know where I can get the wire from the 3192 to the CHM-S620 (cd changer)?

No worries, I need that cable...yesterday. If you have a lead on one of the cables or what pins I could solder leads to, that would be absolutely great.

@JoeyManhattan, Does your Yatour/Bluetooth module have any flashing red lights? If nothing is flashing, then I agree ---- your Yatour / BT module is not getting power. Also, if your BE1432 says "CD E" on the headunit then it soooooooounnnds like your headunit thinks that its connected to a CD player that has an error ---- that's GOOD --- because I think that means your MX3192 is working?

@sPoTwArEz, @kre8tive202, @JoeyManhattan --- I don't know why I didn't think of googling the this before ---
I just did a google search for "Alpine MBUS Pinout" --- here it is.

The whole point of this pinout is to take power from the rectangular Mercedes connector and put power onto the 8-pin round DIN cable to feed the Alpine CD Changer (or Yatour). Good luck.



EDIT - There seems to be three MBZ/E-ALP cables on ebay right NOW for $25. NOS OEM Interface Mercedes 190E To Alpine Cd Changer Converter | eBay

 

[JoeyManhattan]

@JoeyManhattan, Does your Yatour/Bluetooth module have any flashing red lights? If nothing is flashing, then I agree ---- your Yatour / BT module is not getting power. Also, if your BE1432 says "CD E" on the headunit then it soooooooounnnds like your headunit thinks that its connected to a CD player that has an error ---- that's GOOD --- because I think that means your MX3192 is working?

@sPoTwArEz, @kre8tive202, @JoeyManhattan --- I don't know why I didn't think of googling the this before ---
I just did a google search for "Alpine MBUS Pinout" --- here it is.

The whole point of this pinout is to take power from the rectangular Mercedes connector and put power onto the 8-pin round DIN cable to feed the Alpine CD Changer (or Yatour). Good luck.

View attachment 90843 View attachment 90844 View attachment 90845

EDIT - 2019-11-21 9.21PM PST --- Someone has great luck tonight. There seems to be a SUPER-NLA MBZ/E-ALP cable on ebay right NOW for $25. NOS OEM Interface Mercedes 190E To Alpine Cd Changer Converter | eBay

Appreciate the leads, I searched and found the part number for the adapter. I literally just bought the one you linked, just have to get the seller to ship to FPO.

 

[Jlaa]

Appreciate the leads, I searched and found the part number for the adapter. I literally just bought the one you linked, just have to get the seller to ship to FPO.

I'm amazed that the seller has three available. It just went down to 2 available and 1 sold. Putting this image here for posterity so that future folks know what this cable is all about:

 

[Jlaa]

Here is another MX3192 on ebay. Assuming it works, it is a good deal --- only $99!

Mercedes Benz Disc changer control MX3192 ZB Verstarker BE 1432 1480 1430 1460 | eBay

Stereo's such as Becker BE 1432 1480 1430 1460 1470 are compatible with this unit. All the wires and cables you need are included with this interface.

www.ebay.com

I am not sure if the black cable on the far left of the ad is an MBZ/E-ALP cable though --- a buyer would have to verify it.

 

[JoeyManhattan]

So I got everything hooked up today and the Yatour will not power up still.

I’m at a loss.

This is the unit I purchased: Yatour USB SD AUX Adapter + Bluetooth for Alpine MBUS-BT | eBay

Maybe it’s the wrong one? Any help would be appreciated.

 

[Jlaa]

That looks to be the correct Yatour --- the MBUS one. Consider the following troubleshooting steps:

a) Does the bluetooth module have power? There should be red flashing lights.
b) If the BT module does not have power, then does the main Yatour unit have power? What happens if you jack into the main Yatour unit with a 1/8" mini-plug from your phone? Note that there are no flashing lights on the Yatour, but your Becker 1432 should say "CD 52" on the display
c) Working backwards yet again, does the MX3192 have power? Again there are no flashing lights on this thing, but one approach to verify if the Mx3192 is working is to swap out the Yatour for a known good Alpine changer, as indicated in the beginning of this thread.

Lastly ---- pictures of every single connection would help!

 

[JoeyManhattan]

There are no lights anywhere on the Yatour bits at all, and the head unit still reads “CC E” on the display. It does not appear to recognize the Yatour.

The connections are exactly, and I mean exactly as the pictures earlier in the thread show. The only difference being that I had to wiretap the power and ground into the new harness to the Yatour due to there being no “Y”. The taps are solid, and I tested the connection.

I have no CD changer to test this at all, and honestly am not going to buy one to do so.

 

[Jlaa]

Well then, given that the there are no flashing lights whatsoever on the Yatour bluetooth module (and there should be, because application of power should put the bluetooth module in pairing mode), I think it is safe to say that your immediate avenues of troubleshooting possibilities are:

a) the Yatour main unit is not getting power OR
b) the Yatour main unit is broken

What does voltage look like across pins 6 / 8 and 7 / 8 on the DIN cable that goes to the Yatour from the MX3192? Note that those mercedes rectangular 4-hole power connectors are very fiddly. Often times they look like they are making contact when actually they are not. I cannot stress this enough -- I have spent MANY HOURS troubleshooting power-up problems with my own Yatour before, only to realize that the problem is with the mercedes rectangular 4-hole connectors not making contact.

By starting troubleshooting backwards from the very end of the chain, you can work your way up to the MX3192. The only way I know how to test the MX3192 is to plug a known good CD changer into it.

 

[JoeyManhattan]

So I figured out pin 6 is not getting power, once I rectify that I should be good.

 

[Jlaa]

So I figured out pin 6 is not getting power, once I rectify that I should be good.

Fingers crossed for you....

 

[JoeyManhattan]

Well I tied for power to the pin, it powers up and connects to my phone, still get this:

 

[JoeyManhattan]

After more digging, that code is for the cassette, so the unit is not recognizing the adapter.

 

[Jlaa]

Press mode. Can you list out all the modes the headunit cycles through?

 

[JoeyManhattan]

Radio Aerial, Cassette. Is there something that has to be done to enable the CD player?

 

[Jlaa]

Radio Aerial, Cassette. Is there something that has to be done to enable the CD player?

So its a good thing that the Yatour is powering up --- that's progress.

You should see three modes like in my photos below.



Firstly, please make sure the MX3192 is getting power!
Secondly, I read before that it is best to disconnect power to the car (disconnect the battery) for 15 minutes, disconnect the cables to the MX3192, and let things settle. Then reconnect the cables to the MX3192 and the reconnect the battery.
Then, double, triple, quadruple check that your MX3192 is getting power. Those mercedes rectangular connectors are finicky.


EDIT --- Found the reference --- go here. changer adaptor - PeachParts Mercedes-Benz Forum Scroll to comment #12. This is where @2phast was recommending disconnecting the battery. Reason is to make the headunit / tuner module "forget" what modes is has and to "reinitialize" when the battery is reconnected so that it think it can have a CD changer mode.

 

[Jlaa]

BTW, I just want to make sure your signal cable (DIN) wiring is correct. Originally, before you started this project, you had a white cable that goes into your tuner module right? Let's call this White cable plug W. So it used to be W --> Tuner Module, correct?



With the MX3192, now you have W --> MX3192 --> Tuner module ---- correct?
And you are only using ONE DIN receptacle on the tuner module right? Like the picture?

 

[JoeyManhattan]

So I left it disconnected for about an hour, no change. The original plug leads into the “left” plug of the MX, then leads out of the “right” and into the tuner.