Ronnoc Nailli

i have been working on this backup camera on my wife's 2010 c300 since yesterday morning. it's killing me.

what i've done:
installed camera to trunk lid and made appropriate connections
routed video cable to COMAND unit
connected fakra/rca adapter, connected video line to COMAND
enabled SRVC in eng.menu
system reset

what it's doing:
shift into reverse, black screen with text and guidelines

troubleshooting:
1. removed fakra/rca adapter, brought an extensions cord and 19" tv out to the car, and confirmed that the camera is outputting video to the end of the line
no way to test throughput of fakra/rca adapter
2. reconnected original green fakra for iPod kit, connected old Nintendo
deactivated SRVC in eng.menu, corrected setup for aux.video
switch input to aux video with OEM connections: black screen
tried connecting nintendo to 4pole 3.5mm multiplug, still black screen
tried connecting nintendo with new fakra/rca adapter, still black screen
3. visual inspection of fakra port on COMAND unit, it looks fine
visual inspection and comparison of OEM and new fakra plugs, both look the same and fine
4. confirmed NTSC settings in COMAND

the only thing i haven't tried is loading a video on this ancient iPod i have, and trying to play aux video through the 30pin dock connector

has anybody else encountered this? the troubleshooting i've performed indicates that my COMAND unit isn't capable of accepting/displaying video through the aux fakra. that would be a terribly inconvenient truth.

Ronnoc Nailli

well, as it would seem, this fakra/rca adapter has a short circuit, the two poles show continuity.

does anybody know if that could/would damage the COMAND unit?

i never tested the aux.video functionality before connecting the backup camera, but i've pulled the COMAND unit and i'm measuring 78ohms of resistance between the inner pin and the sheath.
i'm not particularly knowledgeable about "what to expect" but the internet says i should expect 75ohms resistance on a coaxial a/v/data line, compared to the .8ohm short on this fakra adapter.

this stinks

Ronnoc Nailli

resolution:

disassembled and rebuilt the fakra. this was an $8 ebay cable from china, go figure.

C300CA

75 ohm is the characteristic impedance of a video coaxial cable, not the DC resistance measured with a DMM. Any coaxial cable should be DC open between the center conductor and the outer shield.

Ronnoc Nailli

well shoot.

-1 for my tenuous grasp of low voltage electronics

i measured the resistance between center and shield on the COMAND unit, which read ~75ohm as opposed to the cable's 2-3ohm.. to quote cablesondemand:

“The characteristic impedance of the coaxial cable (in Ohms) is determined by the dielectric constant of the inner insulator and the radii of the inner and outer conductors.”

which to me reads, the impedance between inside and outside.

operating under the assumption that i correctly understood the situation, i completed the repair and thankfully it worked.

IloveC300

Guys, i also got everything wired up and the screen shows nothing when in reverse. I dont have any monitor/tv to test out if the camera works or not. is there any other way i can test to see if camera outputting anything? i bought camera and fakra cable almost 4 years ago.. just got to install it.. so not sure if camera is still working.

Ronnoc Nailli

i found that the FAKRA adapter was difficult to fully seat into the COMAND unit. i ended up removing the plastic jacket and inserting the core connector only. it's still a snug fit, and that made plugging in the LVDS connector next to it easier

without having a TV or screen of some sort to test the camera, there's not a whole lot you can try...

use a multimeter or the like to test the power/ground at the camera when it should be on
test the continuity of the video cable you've run to the COMAND unit
test the continuity of the RCA/FAKRA adapter (if you've bought cheap chinese one like me, it may be bad or out of spec for the job)

if the camera isn't fully installed to the trunk lid, you may consider bringing the camera inside and connecting to your home TV, and trying to find a 12v power supply to turn it on there.

you could also enter the engineering menu and disable SRVC and enable AUX.video... then select AUX.video on the COMAND unit... this could possibly determine that the camera is correctly installed and that the SRVC isn't configured correctly in COMAND.

good luck

IloveC300

i should be able to remove it from the trunk lid. i didnt seal the trunk yet so i'll be able to take it out. I checked the wires and they all are securely connected. also i pushed the fakra the way in to make sure it was securely connected. but yes if the issue is cable like yours then i'm screwed.
​​​​​​​thanks for the suggestions..

Ronnoc Nailli

do you have access to a multimeter?

it was a pretty simple task to resolver the FAKRA connector if you're at least a novice with an iron

what part of seattle metro are you in? i'm in SKC

meazz1

I run into an issue like black screen when I installed camera on my wife's van.
I forgot to remove the protective cap from the camera, it took few hours of serious troubleshooting

IloveC300

I'm in Snohomish in Bothell.

IloveC300

😂 Mine didn't come with any cap.