C-Class Radio/Screen Issue After Boosting Battery

[Aleksandar Tepsic]

Hello everyone,

Below is a chronological list of events that occurred which describe the issue I am having with my girlfriends 2010 Mercedes Benz C300 and my process thus far.
[b]
Summary of events:[/b]
1. No crank, no start scenario. Diagnosed dead battery.
2. Accidentally reversed polarity for a few seconds while trying to boost battery :pinch: :angry: . After this stupid mistake, successfully boosted the battery. However, new problem arises, crank but no start.
3. Diagnosed and replaced blown fuel pump fuse. Car starts and drives normally.
4. Everything operates as it should except screen/radio, they are both completely off and do not turn on. The screen does not come out of the dash and nothing on the radio works, no music, no lights, nothing. Checked all fuses, found no other blown fuses.
5. Removed and replaced radio/screen fuses to “hard” reset the system as per instructions on Mercedes forum. No luck.

My next steps are to remove the radio/screen units (they are separate) and to inspect the electrical components. Does anyone know whether such units in general have any internal fuses that would be worth inspecting or any other things I can check before I begin disassembly? I feel like there must be some sort of reverse polarity protection within the units and I am optimistic that I didn’t just fry the radio/screen as a result of improper boosting. I am open to suggestions/ideas if anyone has any.

Also, I’ve searched for technical documentation on the radio/screen but no luck. I couldn’t find a complete electrical diagram of the vehicle either like I did for my Volvo S60 so I feel blind going into this.

Topic

[college man]

see if this helps with fuse locations.

http://www.mercedesmedic.com/no-sound/

[Aleksandar Tepsic]

Thanks for the reply. I checked all the fuses in the fuse boxes but I will double check before I disassemble anything. I was wondering if there are any other fuses in the unit itself, an internal one. I could be way off to even assume that but it’s something I’m thinking about.

[college man]

[quote=”Ace Enthusiast” post=181699]Thanks for the reply. I checked all the fuses in the fuse boxes but I will double check before I disassemble anything. I was wondering if there are any other fuses in the unit itself, an internal one. I could be way off to even assume that but it’s something I’m thinking about.[/quote]

Shouldn’t have a fuse in it.

[lee brown]

there will most likely be some reverse polarity protection inside the units however it is unlikely that these will be replaceable by your self as they will probably not even look anything like a fuse i would suggest that you google search for a repair company that deals with these units to recondition them and phone that company to explain what happened and go from there im sorry that this isn’t an easier answer but in my opinion it is probably your best option to get this fault repaired

[Aleksandar Tepsic]

[quote=”djexkon” post=181830]there will most likely be some reverse polarity protection inside the units however it is unlikely that these will be replaceable by your self as they will probably not even look anything like a fuse i would suggest that you google search for a repair company that deals with these units to recondition them and phone that company to explain what happened and go from there im sorry that this isn’t an easier answer but in my opinion it is probably your best option to get this fault repaired[/quote]

Appreciate the feedback. If I cannot find anything once I remove the unit, then I will most likely do what you have suggested.

[lee brown]

inside the unit will most likely be either metal oxide varistor protection or diode protection or both and possible even a surface mount fuse it would be tiny and most likely not labled hope to be some help please update with your findings
thank you

[Aleksandar Tepsic]

[quote=”djexkon” post=181868]inside the unit will most likely be either metal oxide varistor protection or diode protection or both and possible even a surface mount fuse it would be tiny and most likely not labled hope to be some help please update with your findings
thank you[/quote]

I have some other work to do on the car before I get to the radio, but once I finish that I will disassemble and do some tests. First thing to check is whether or not the radio is receiving power. If it is, then I will have to open it up and see what’s inside. Will be doing it with my friend who is an electrical engineer. I will be back here to post findings.

[Aleksandar Tepsic]

An update to my issue for others that might have this problem in the future. After removing the radio, I was happy to find that there was a fuse and even more happy to find that it was burnt, because it protected the radio which worked perfectly after replacing the fuse. Cheap, quick fix, gotta love it.

[college man]

[quote=”Ace Enthusiast” post=184567]An update to my issue for others that might have this problem in the future. After removing the radio, I was happy to find that there was a fuse and even more happy to find that it was burnt, because it protected the radio which worked perfectly after replacing the fuse. Cheap, quick fix, gotta love it.[/quote]

Glad you found the fuse.

[Author]

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