mike82212

What to do?

For over a year I keep taking my 2014 C300 with premium sound back because the AM radio sounds so bad. I have compared the same station in the same place with another car and that radio sounds just fine. I use AM in the morning for traffic and news.

At 1st the dealer told me no codes so nothing wrong. I took it back several times and the made a fix here or there. I can hear the engine electronic noise come through the speakers. It appeared to be fixed last time, ut then started again

Just talked to the MB service manager and he told be the tech had it working fine, placed the car in reverse and the noise came back. So now they are keeping it even longer as they try and figure out whats wrong

michail71

So you are getting electrical interference from your car?

That could be a tough one. First thing they should try is a donor head unit. Then check wiring for the antenna and all grounding points.

After that it could be something in your car's electrical system.

Do you have any accessory devices attached into any power outlets such as a phone charger, etc.?

mike82212

nothing plugged in. Not sure if they have tried a donor unit. There is a service bulletin to remove the ground wire from the sunroof track and clean and reattach….that did nothing

Yes, its a tough one and Im very frustrated. The loaner doesn't have GPS and we are traveling across state tomorrow

michail71

Hmm, it doesn't mean they fixed the issue correctly. It is something you can easily access and try some contact cleaner on or a small dab of dielectric grease?

mike82212

the entire headliner has to come off to access that point. The service manager said sometimes its ok sometimes it isn't so they are keeping it longer.

I love the car, my 1st MB and 1st German, but Iam getting sick of this issue

michail71

Oh, headliner. That is one of the worst jobs to do on a car.

stgry1

Do you have any aftermarket LED bulbs in the car? After I replaced my eyebrows with LEDs, I noticed that everytime I listen to AM with the parking lights on, I hear much static. Once I turn off the parking lights (i.e. just run with the DRLs) no issue. Like you, I usually catch up in the AM with the news and don't worry to much about the occasional static but sometimes it can be irritating. Not sure if any of this applies but thought I'd share.

michail71

I had an inverter in my previous car that would do stuff like that if in use. These things can be tough to narrow down.

mike82212

The car is stock except for tinting. The static at times is solo bad I can not here the radio.

mike82212

Now the dealer is saying that MB is blaming it on the window tint. Its 3m Cystalline which states its non-matelic and will not cause interference.

I have a loaner, but no GPS or realtime traffic and with my commute each day I need that. They have had the car a week tomorrow

Alfadude

Did the issue start after the tinting was done? If there is any metal in the material I coudl see how that could affect your reception.

mike82212

The tint was applied a few days after I got the car, the problem did not develop till latter

As I stated there is NO METAL in the film. 3M states it will not interfere

michail71

The 3M Crystalline will not cause that. Where is the antenna located? If it's in the shark fin then any window treatment would be ok. But window tinters don't like to use metallic films anymore because of issues it causes with cell phones.

I had my car in over 5 weeks for a navigation system issue. I still have to bring it back because some things had gotten broken or scratched up. Some of it is the time it takes to coordinate with the factory for diagnosis plans. Then it might actually require a significant amount of interior dissassembly.

In my case they just replaced the Comand head unit but they tried a million other things first. I'm not sure why they just didn't try that first.

mike82212

I have no idea where the antenna is. I do know they are talking to MBUSA now. They are replacing the antenna connector now, waiting for a part. Now Im driving a C300AMG, fun! LOL

I will suggest the entire head unit next

mike82212

Well, I keeping my fingers crossed but it appears to be fixed. They replaced the antenna amplifier and also the interface to the antenna amplifier. So I will she if the fix holds

michail71

Nice to see a problem getting fixed!

I'm going on 3 months now with all my little issues. But it's more a matter of getting shops to just do the job correctly that seems to be the hard part.

mike82212

Sad, sad news. They kept my car just shy of 6 weeks. Replaced the Command unit. Took a ride with Tech and shop Forman. Car seemed ok. Got it it the ned day and within 5 mins of driving, problem was back worse then ever.

It almost always gets better when the engine is off

Now they have had it all week and their comments to me, its atmospheric conditions or the tint. Doesn't explain why the loaners don't have it

As I'm typing this a reply from the shop forman:

My reference to atmospheric conditions affecting radio reception is only a supposition on my part based on personal experience in my own vehicles, other customers vehicles, and what we have experienced in your vehicle over the past few weeks. The radio played well on cold rainy days, much better than on warmer dry days. This was only an observation on our part and I have no solid evidence to support that statement. Why do the loaner vehicles seem to fare better? Being newer models they have one or possibly two upgrades on the telematics system that is found in your car, and a better antenna array to support it. As far as the tint is concerned I have no way to test the affect on reception, only to reaffirm my earlier comment that it could possibly be a factor in this case. I did drive your vehicle this morning, and the reception was better than I had experienced yesterday afternoon. 680 came in pretty clear away from power lines and other obvious signal hindrances. In the spots where the static was especially bad I navigated to 1090 which always came in clear, possibly because their transmission is so much stronger. I have left the supplemental ground harness for the coil circuits on the vehicle. Any additional ground paths that can improve AM reception can't be a bad thing.


so Im guessing it will never work correct and they won't do anything for me?

michail71

Oh wow, it has been a while.

I'm sure it can't be the tint. For one it is a non-metallic film and the antenna is external. That's just basic science.

I wonder if replacing coils and or the wiring harness would be worth a check? I recall somewhere in the past reading about a wire harness or coil causing interference.

They could do it from a donor vehicle as a test but I know how frustrating it is to have your vehicle held hostage.

mike82212

I was told the antenna is part of the rear window and the heater elements on that window

I have to admit they have really tried. I have tried to stress the interference appears more engine noise but they have choose not to go down that path