Photos of 2019 Stereo Head Unit and wire harness

Other posts have discussed the stereo head unit and wire harness, but photos have been lacking. I have a 2019 4x4 144 Cargo van that did not come with rear speakers, and the head unit was not programmed to accept or control rear speakers (fader function). I also do not have the EP7 option. I'm working through the process of having the head unit reprogrammed to add rear speaker fader function, and also add wires to the wire harness to take the rear speaker signal to my JL Audio Fix86. Since there is a 5 photo per post limit, i'll divide up my photos btw posts.

Here's what it looks like after you remove the touch screen unit (removal technique has been discussed in other posts). The head unit is the silver square thing and removes easily with 4 torx screws:
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This is the touch screen unit piece that comes off as one piece:
IMG_2076.jpeg

This is the back of the touch screen unit:
6741DBC5-ED60-46DE-B667-66DD12CDA6B6.JPEG

After removing the head unit, you can see all the wires coming out the bottom. I believe the speaker wires are contained in the biggest harness at the bottom edge of the unit (see next photos for more specifics):
IMG_2038.jpeg
 
After removing that big harness containing the speaker wires:
IMG_2072.jpeg


Others have stated that the the left speakers are the white/pink and white/black wires. And right speakers are the Grey/yellow and grey/black wires. In the next photo, you'll see that these wires correspond to the slots next to #13 and #1.
IMG_2058.jpeg


The speaker wires go to the slot pairs to the right of #13 and left of #1. You can see the female metal AMP MCP 2.8 contacts in those slots. (this post lists part numbers for those contacts https://sprinter-source.com/forums/index.php?threads/80621/page-8#post-932996). Notice how the slots next to numbers 26 and 14 are blank and do not contain any contacts. I assume this is where rears speaker contacts/wires would exist if looking at a wire harness from a crew or passenger van with rear speakers. Someone please correct me if i'm wrong. Those empty slots are where I plan to add contacts and wires to take the rear speaker signal to my Fix86 after my head unit gets reprogrammed for rear fader function.
IMG_2068.jpeg

This is looking at the male contacts on the head unit where the wire harness plugs in. The metal shaft is pointing to the prongs where the speaker wire contacts on the harness connect...there are 4 sets of those prongs.

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Side view of removed wire harness:
IMG_2069.jpeg


If someone knows better and feels I have given incorrect information, please correct me. I am not a stereo install professional. I'm just trying to piece together information from various posts.
 

JudoFish

New member
Who is reprogramming your head unit for rear speakers? Is there an easier way to use an amp/equalizer? I am about to go in with JL Audio front and rear speakers along with the Alpine slim line powered sub. Thanks for the detailed photos!!!!
 
Who is reprogramming your head unit for rear speakers? Is there an easier way to use an amp/equalizer? I am about to go in with JL Audio front and rear speakers along with the Alpine slim line powered sub. Thanks for the detailed photos!!!!
Mercedes Benz of Draper in SLC Utah is attempting to do the reprogramming. It's the first time they have done it and their first attempt was a fail...so they are re-trying today. Mercedes of Sacramento and others have successfully done this reprogramming multiple times (I spoke to them over the phone). The dealership has to request software and codes from Mercedes. Then it takes a few hours to download the software and then upload it to your van. After their first attempt, my entire computer system would not turn on...only a black touch screen with "Mercedes Benz" across the screen.

Members on this site have described other ways to control rear speaker volume such as adjusting gain through the Amp. However it's my understanding that these other methods are not optimal...it's better to have fader control through the head unit. A signal processor btw the head unit and amp (eg Fix86) has been highly recommended to me, which is why i'm using the Fix86. I'm sure there are lots of other ways to jimmy-rig the system to produce a good sounding audio system with appropriate controls, but I'm not a car stereo install expert and I want things to be simple to control and operate once installed.
 

VanGoSki

Well-known member
A few hours? MB of Modesto added my rear fader control for me for free the day I picked up my van in like 10 or 20 minutes.
 

sanomechanic

Well-known member
A few hours? MB of Modesto added my rear fader control for me for free the day I picked up my van in like 10 or 20 minutes.
Yea but didnt you already have the EP7 option? If so all they have to do is activate "turn it on" with scan tool.
If you do not have EP7 it requires a complete re-flashing which requires a software release from MB. If the monkey does not know what he is doing it corrupts the ECU/Processor. Some times requiring unit replacement.
Still the re-flash would not take a few hours. They just want the van a few hours to contacts MB, get the release of the new flash data, add it to Netstar then flash the van
 

sanomechanic

Well-known member
After removing that big harness containing the speaker wires:
View attachment 157768


Others have stated that the the left speakers are the white/pink and white/black wires. And right speakers are the Grey/yellow and grey/black wires. In the next photo, you'll see that these wires correspond to the slots next to #13 and #1.
View attachment 157769


The speaker wires go to the slot pairs to the right of #13 and left of #1. You can see the female metal AMP MCP 2.8 contacts in those slots. (this post lists part numbers for those contacts https://sprinter-source.com/forums/index.php?threads/80621/page-8#post-932996). Notice how the slots next to numbers 26 and 14 are blank and do not contain any contacts. I assume this is where rears speaker contacts/wires would exist if looking at a wire harness from a crew or passenger van with rear speakers. Someone please correct me if i'm wrong. Those empty slots are where I plan to add contacts and wires to take the rear speaker signal to my Fix86 after my head unit gets reprogrammed for rear fader function.
View attachment 157770

This is looking at the male contacts on the head unit where the wire harness plugs in. The metal shaft is pointing to the prongs where the speaker wire contacts on the harness connect...there are 4 sets of those prongs.

View attachment 157771


Side view of removed wire harness:
View attachment 157772


If someone knows better and feels I have given incorrect information, please correct me. I am not a stereo install professional. I'm just trying to piece together information from various posts.
Can you determine which is left and right, positive and negative terminals?
 

sanomechanic

Well-known member
Mercedes Benz of Draper in SLC Utah is attempting to do the reprogramming. It's the first time they have done it and their first attempt was a fail...so they are re-trying today. Mercedes of Sacramento and others have successfully done this reprogramming multiple times (I spoke to them over the phone). The dealership has to request software and codes from Mercedes. Then it takes a few hours to download the software and then upload it to your van. After their first attempt, my entire computer system would not turn on...only a black touch screen with "Mercedes Benz" across the screen.

Members on this site have described other ways to control rear speaker volume such as adjusting gain through the Amp. However it's my understanding that these other methods are not optimal...it's better to have fader control through the head unit. A signal processor btw the head unit and amp (eg Fix86) has been highly recommended to me, which is why i'm using the Fix86. I'm sure there are lots of other ways to jimmy-rig the system to produce a good sounding audio system with appropriate controls, but I'm not a car stereo install expert and I want things to be simple to control and operate once installed.
My Left a Right speaker wires are split into my FIX 86 L 1&5 R 2&6.....Do not have fader control but audio defiantly sounds 100% better.. Have the gains set to equal power/sound from ft to rr. Please keep everyone posted on you success. Please document what are the positive and negative terminals and the success on re-flashing. Great photos thanks
 

VanGoSki

Well-known member
Yea but didnt you already have the EP7 option? If so all they have to do is activate "turn it on" with scan tool.
If you do not have EP7 it requires a complete re-flashing which requires a software release from MB. If the monkey does not know what he is doing it corrupts the ECU/Processor. Some times requiring unit replacement.
Still the re-flash would not take a few hours. They just want the van a few hours to contacts MB, get the release of the new flash data, add it to Netstar then flash the van
Yes on the EP7. But according to the dealer ordering guide, EP7 is only pre-wiring. If it was also additional firmware then why didn't I already have the fader control? To me it seems unlikely that there are TWO different flashes needed to get rear speakers. But what do I know.
 

sanomechanic

Well-known member
Yes on the EP7. But according to the dealer ordering guide, EP7 is only pre-wiring. If it was also additional firmware then why didn't I already have the fader control? To me it seems unlikely that there are TWO different flashes needed to get rear speakers. But what do I know.
If you have EP7 then MB gives the green light to enable since it is already part of the build. In other words they can connect scan tool and turn on a channel that already exists. If a van does not have EP7...then MB has to approve the changes, release a re-flash then add that option to the VIN number in the Netstar Database. My understanding MB is really strict about this stuff
 
My Left a Right speaker wires are split into my FIX 86 L 1&5 R 2&6.....Do not have fader control but audio defiantly sounds 100% better.. Have the gains set to equal power/sound from ft to rr. Please keep everyone posted on you success. Please document what are the positive and negative terminals and the success on re-flashing. Great photos thanks
At this point I don't know which is positive vs negative. I'll update my post as I learn more
 

spitfirefd

New member
Does anyone know what the connection is labeled for the satellite antenna? I purchased the factory cable and antenna to add satellite radio and would like to install the cable and antenna prior to having a dealership reprogram the MBUX system to add satellite radio.
 
I think you can use a multimeter to figure it out. if the numbers go negative, the polarity is reversed. If numbers are right the red lead is positive
I'm planning to play around with the multimeter for polarity and to check wire continuity to see which wire at the speaker corresponds with the wire at the head unit (since someone on this forum has stated that the wire color changes somewhere btw the head unit and the speaker). I'm hoping using these 2 methods will help me figure it out
 

sanomechanic

Well-known member
I'm planning to play around with the multimeter for polarity and to check wire continuity to see which wire at the speaker corresponds with the wire at the head unit (since someone on this forum has stated that the wire color changes somewhere btw the head unit and the speaker). I'm hoping using these 2 methods will help me figure it out
If you connect the meter leads to the speaker wires set on AC voltage. Turn volume up some. If the numbers stay in positive range then the positive and negative should be same as you multimeter leads. if it show a minus on numbers. reversed polarity. You should call a car audio shop to verify this but...makes perfect sense to me.
I tried to get MBLN to print audio wiring diagram. Acted like this is top secret info. They are jerks. One of many reasons I will never do business there again.
 

spitfirefd

New member
Does anyone know what the connection is labeled for the satellite antenna? I purchased the factory cable and antenna to add satellite radio and would like to install the cable and antenna prior to having a dealership reprogram the MBUX system to add satellite radio.
bump....
 
Here are a few things I discovered today. First of all the AMP MCP connectors described at here https://sprinter-source.com/forums/index.php?threads/80621/page-8#post-932996 are not the correct size connectors for the speaker wires slots in the head unit wire harness. Those connectors are too large and likely fit the 4 large rectangular slots in the corners of the harness. I am now trying to find the correct size.

Also, I did some polarity testing and wire continuity testing using these methods:

This is what I found.

Regarding the drivers side door speaker: The Gray/white wire plugging into the speaker is positive, and corresponds to the Pink/White wire coming out of the head unit wire harness. The Green wire is negative, and corresponds to the Black/White wire coming out of the head unit harness. These wires change colors right after passing through the rubber accordion boot on the door using a plastic connector. Who knows why the wire color changes.
Regarding the passenger side door speaker: The Gray/white wire is positive and corresponds to the yellow/gray wire on the head unit wire harness. The Purple wire is negative and corresponds to the black/gray on the head unit.

Here is the main wire harness after removing the zip tie and casing. Notice where the speaker wires come out:
IMG_2151.jpeg

IMG_2152.jpeg

This Is a sketch of the underside of the harness showing which slots correspond to wires and the polarity is show with +/-.
IMG_2157.JPG

This is the passenger door after removing the wire boot and pulling the wires out a bit. This is where the wires change color. See next photo for better orientation.
IMG_2147.jpeg

Zoomed out for better orientation:
IMG_2148.jpeg
 

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