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Radio/infotainment harness repair. Serious help needed

noradio

New member
Location
North Carolina
Car(s)
2015 GSW TDI 6MT
Hello all! First post here, wish I didn’t need to get help for this but here I am (sorry this is probably going to be confusing and convoluted):

Couple months ago bought a '15 Sportwagen TDI S six-speed at an insurance auction. I really like the car and have been driving it after I finished repairing the crash damage. However, I have an issue with what the previous owner did to the car. I found the car with no display or unit in the glovebox, only an absolute mess made of the wiring harness. He put in an aftermarket unit (and I guess ripped it out after the crash) and based on how he did it he should be institutionalized. Anyway, pictures show what I'm left with.

20241214_180024.jpg
20241214_154429.jpg


I want to put a Volkswagen system back in the car. I’ve done a good bit of research on MIB2 installs and what’s been documented so far is pretty thorough. In normal circumstances I would just do the MIB1 to MIB2 install (non-Fender) no/few questions asked… but my issue is obviously getting to the starting point of the conversion I.E. the wiring harnesses need repair.

SO… what I’ve done so far:
  • Gotten a copy of the wiring diagrams from Erwin (seems like it’s incomplete though? Only goes to 500 pages and it seems like connector pinouts are cutoff. Does anyone know how long the document should be for “MEX5R010521-Wiring_Diagrams_and_Component_Locations”?)
  • Documented the state of the cut harness in the car with many pictures
  • Determined 2/6 coax lines are cut
  • Started trying to match my cut harnesses to the diagrams in section 24
I have no problem splicing together a new harness from a donor car by soldering and heat shrink (if I can find donor harnesses which I also need help with if anyone is parting out a car) but I have the following ISSUES:

Outstanding questions and issues:
  • Coax cables…I don’t see them in the wiring diagrams… can someone help identify them? What coax cables should I expect to find in a 2015 MIB1 non Fender system and where are they supposed to connect to? Where do they come from?
    • Two coming from the passenger A pillar area (blue/pink):
      • 20241214_155601.jpg
        20241214_155611.jpg
        20241214_155617.jpg
    • Another two (black) are coming from the rest of the harness out of the dash - no colored connector just plain metal crimped ends:
      • 20241214_183909.jpg
    • Last two I found have been cut and spliced into, no idea what any of them are for specifically
      • 20241216_210352.jpg

  • CANBUS pairs
    • I have two pairs of cut CANBUS high/low lines in the car. One pair definitely goes to the grey 12-pin connector T12al pin #s /12 and /6:
      Screenshot 2024-12-16 205435.png
      . However, that cut connector that I have in the car also appears to have another pair of CANBUS lines in /1 and /7 but I cannot find this pair in the wiring diagrams:
      • 20241214_184609.jpg
    • I also don't know how to identify which pair is which on the car side as they kinda come out of the same bundle, both pairs shown here:
    • 20241214_184915.jpg
Ummm... so what does anything think? I'll appreciate any input I can get 😬
 
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2018gti

Drag Racing Champion
Location
Boston, MA, USA
Car(s)
Golf GTI Autobahn MT
that is absolutely horrific, I'm sorry. those 2 CAN bus pairs that you have, one pair is the infotainment bus (6, 12) and the other pair (1, 7) goes to the screen. just off the top of my head, if you wanted to figure out which one is which, with the ignition on and no screen plugged in, only one of the pairs will be 'live' and have a voltage on them (the infotainment CAN). or, maybe better, do a continuity test from the plug that goes to the (missing) screen to one of the bare CAN pairs.

for the coax/fakra, I don't know 100% about MIB1 unfortunately but take a look at page 11 of this for some ideas: https://static.nhtsa.gov/odi/tsbs/2016/MC-10121137-9999.pdf (edit: this one seems to be for MIB1 - https://static.nhtsa.gov/odi/tsbs/2014/MC-10122164-9999.pdf)

my guess would be the previous owner 100% destroyed the AM/FM ones (one pair of black coax) so the new "radio" could tap into them. then you have video signal to the screen (pink), satellite radio (brown), GPS (blue). I'm not 100% on the GPS and the other two black coax wires, though. also, I'm only familiar with the USB port and that has a yellow connector like the pink one.
 
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noradio

New member
Location
North Carolina
Car(s)
2015 GSW TDI 6MT
that is absolutely horrific, I'm sorry. those 2 CAN bus pairs that you have, one pair is the infotainment bus (6, 12) and the other pair (1, 7) goes to the screen. just off the top of my head, if you wanted to figure out which one is which, with the ignition on and no screen plugged in, only one of the pairs will be 'live' and have a voltage on them (the infotainment CAN). or, maybe better, do a continuity test from the plug that goes to the (missing) screen to one of the bare CAN pairs.

for the coax/fakra, I don't know 100% about MIB1 unfortunately but take a look at page 11 of this for some ideas: https://static.nhtsa.gov/odi/tsbs/2016/MC-10121137-9999.pdf (edit: this one seems to be for MIB1 - https://static.nhtsa.gov/odi/tsbs/2014/MC-10122164-9999.pdf)

my guess would be the previous owner 100% destroyed the AM/FM ones (one pair of black coax) so the new "radio" could tap into them. then you have video signal to the screen (pink), satellite radio (brown), GPS (blue). I'm not 100% on the GPS and the other two black coax wires, though. also, I'm only familiar with the USB port and that has a yellow connector like the pink one.
This is very helpful, thank you!

Good to know one of the CAN pairs goes to the screen, testing continuity should solve that as you say.

Those links are very helpful to reference what connections there would normally be.

Everything makes sense except those two plain coax's that are untouched. It makes sense that he would have tried to tap into the AM/FM pair, but then what else would the other ones be? Until you said that I thought they were the radio signals.

Regardless, I think this gives me enough to repair the harness and attempt the upgrade. Worst case I won't have radio, which is fine. I just need Bluetooth, and AA once in a while
 

2018gti

Drag Racing Champion
Location
Boston, MA, USA
Car(s)
Golf GTI Autobahn MT
those extra two black coax, yeah, honestly I don’t know. if someone who knows MIB1 better can comment then that would be helpful.

do you have a USB port in the center console? if you have the old MDI port instead then that may explain the difference. but honestly I have no clue.

you know, I do see in your picture of behind the missing screen, there are two coaxes there too, which seems kind of weird to me - there aren’t any coaxes that normally go to the screen (besides the video cable). is it possibly something extra left over from the previous install?
 

noradio

New member
Location
North Carolina
Car(s)
2015 GSW TDI 6MT
No USB, I have the old MDI port which I will be stealing power/ground from for the USB plug.

The two coaxes behind the missing screen is how I found them. I since pulled them into the glove box, so that's why there are pictures of them in those two spots lol. All the cable sheaths of the coaxes look to be stock with markings "Made in Czech Republic" and such. If I can get the wiring repaired and get a MIB2 unit in there, then I'll just test them and see what happens I guess
 

2018gti

Drag Racing Champion
Location
Boston, MA, USA
Car(s)
Golf GTI Autobahn MT
ah I see, yeah, sounds like they were always there then. still no clue for me other than somehow your Wagen had a cellular connection from factory. the cellular/GSM module is the only other thing I know that uses a pair of coax, but it’s only Audis that get cellular features on the MIB over here. it is a 2015 so, maybe they were thinking about supporting it but then decided not to?
 

noradio

New member
Location
North Carolina
Car(s)
2015 GSW TDI 6MT
Update:
I got the wiring all spliced together correctly (I think). I now believe the strange coax's that are broken out with crimps is stock VW... One pair is for the reverse camera that goes to the blue 12 pin /1 and /7, and the other is for the microphone that goes to blue 12 pin /6 and /12 (or the other way, don't remember off the top of my head). I realized this after looking at enough pictures of the connector online and seeing similar loops of the white wires. I know this is correct because my reverse camera works now!

For the MIB2 conversion/coding portion, I got a 6.5" screen 3G0919605H and the glovebox unit 3q0035844. It has software train MST2_US_VW_P0504D. I ran the v3 Congo and Duke activator, however was not able to get it to automatically run the CP patch script off the SD card on reboot. So instead I did the telnet method through ethernet, backed up what was on there, and updated the delphibin.ifs with the CP patched one. It does work...temporarily. The "component protection active" watermark is gone. But the audio will only work for somewhere between ~1-10 min, have not noticed a pattern yet. When it shuts off there's a strange noise and all audio goes away. If I try to adjust volume with the volume knob then the slider scale pops up on the screen but the slider does not move. I can reboot the system to regain audio temporarily again.

Thinking there were some adaptations not set correctly I checked what I could referencing this and disabled the drive mode adaptations that were enabled, and changed the vehicle type to Golf variant/wagen in byte 0, but that is the extent of my knowledge.

Has anyone encountered this issue of audio cutting out after a few minutes of being on? Either it's a hardware issue with the unit (relatively easy to check, would probably try a 3q0035844B unit next), an issue with the coding/adaptations, or an issue with the wiring I repaired (could there be some weird interference going on? I kept the twisted pairs as tight as I could for the CAN and speaker pairs)

I'll be digging through the 119 page conversion thread for any similar issues in the meantime...
 

noradio

New member
Location
North Carolina
Car(s)
2015 GSW TDI 6MT
Closing out this thread with some more detail incase it can help anyone else. TLDR finally got everything working after a new unit and downgrading FW to 0867D. Looks like my wiring repairs were correct :cool:

Long version: Could not figure out why my first 3q0035844 unit with MST2_US_VW_P0504D was having this audio issue. Decided it was a hardware issue and I got another unit, this time a 3Q0035844B since it's a newer revision. It came with MST2_US_VW_P0890D, which I thought was fine since there is a CP patched delphibin.ifs for that train. However, after updating the delphibin.ifs with the patched file, the unit got stuck in boot loop. If I plugged in the ethernet adapter fortunately it stopped looping and just stayed on a black screen and I was able to connect through putty and restore the unit with the original delphibin.ifs. I attempted a couple modifications to the procedure but every attempt with 0890D ended with the unit boot looping. Finally decided to downgrade the FW to 0867D since there is a CP off patch for that train for STD2Plus. I could not find any CP off patched delphibin.ifs for newer FWs so that is why I downgraded 0890D -> 0867D. After updating to 0867D and using the CP patched delphibin.ifs for that train, everything is working as it should. Took almost two months, it should've been more like a few weeks if it wasn't for the initial faulty unit, and then trouble with the second, but am happy to have it working and to move on to the next project. Now I need to change my username :LOL:
 
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