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Lately I have noticed if I turn the Volume knob quickly either direction it’s not increasing/decreasing the volume quickly. Almost as if it’s not registering every click of the knob turning.
the steering wheel controls are fine.
I read forums where they say to spray contact cleaning but I don’t want to make matters worse and this is an expensive piece to mess up.
i took off the knob and didn’t see anything a miss.
Same, mine’s been like that for the last 3yrs roughly, it occurred just before I had dropped my car’s off with Mercedes in 2017 for an insurance claim.
About the same time my Command control knob stopped working correctly. I’m going to order the new pin mechanism to repair command knob but wondering what to do about main radio knob.
The volume knob on the radio is known to be prone to this issue. My best guess is that it's a type of potentiometer with brass "fingers" that slide across graphite contacts. Over time crud builds up and increases resistance between the fingers and contacts. The only fix for this would be to take apart the radio and clean the contacts inside the knob.
DO NOT spray any contact cleaner into the knob without disassembling the radio first.
One way to test to see if this is the case is by firmly pushing the knob into the radio while turning it. If it improves the responsiveness then the issue is as described above.
I've been procrastinating on doing this to my radio.
There is no brass pieces on the knob, you can easily remove the volume knob and power button by just gently pulling and push it back in snap it back into place the same way.
the knob and button is all plastic.
im still unsure as how it works.
i did pull the battery and put it back if this was a software issue. If continues tomorrow I will spray compressed air in there from a compressor and see if that removes any dirt or grime.
I don’t know what it is with these cars that such dumb stuff breaks that I’ve never had to change in any car I’ve ever owned.
last month I dealt with the crickets from the blower fan, had to remove it, disassemble it and oil it. It was fine for weeks then for only 1 day the crickets came back only if I turned the wheel to the left while driving and making a turn. Then it went away again. like wtf. And I’m 100% it was the blower because when I turned off the air it was gone.
If the volume knob is a potentiometer design then there will be contacts inside. You won't see them by removing the plastic knob. They're literally inside a sealed housing that's soldered to the circuit board.
This is a basic design:
The switch on the actual radio will be smaller and more advanced but similar in design. The common failure of these switches is the buildup of crud between the wiper and resistor. Cleaning this will restore responsiveness.
Spraying compressed air into the knob is probably not going to do anything. The switch is most likely sealed and the air won't get inside it. If it does it will just blow the crud around inside the switch and not out.
I haven't taken apart my radio yet but I'm planning on it at some point so I don't know how difficult the solution is at the moment.
I don’t have the knowledge to fix the issue, I think someone else whom posted was more aware of how to fix potentially.
you have to open the radio, remove the circuit board and then open the component on the circuit board to clean it.
this is worrying as if you make a mistake you have a bigger problem on your hands. Instead of a knob with poor response you won’t have a volume knob on the radio at all.
you would then need to replace the whole command unit.
Mine has been slow to respond in the past. I think that might be because for the most part I always use the steering wheel controls. What I do is turn the radio off and then quickly turn the know to the left a number of times and to the right a number of times and the response returns. What I think is happening is over time the contacts get a little tarnished. Moving it around helps polish the contacts a bit. At least that is my guess. Give it a try.
I tried this but seems to fall back in its old ways almost right away.
if anyone is interested in looking at the mechanism just gently wiggle and at the same time pull off the volume knob, this will pull off along with the power button. To put it back line it up and gently click back into place.
I looked at this slightly more closely today. I don’t know how it works... it seems the volume knob has 3 slots that it fits into and turns a ring that spins around in a housing.
Here is a pic. The square / circle thing in the middle is only the power button and has nothing to do with the volume. It doesn’t even move....
you can see I pointed out the 3 slots the volume knob connects to that spins that ring around which seems to sit in another circular housing
I don’t understand how it works. It also appears to have some sort of grease on it to help it move.....
the knob is physically clicking when you turn the knob, some contact is dirty somewhere and I don’t think WD40 going to solve anything if anything may actually damage the electronic parts + plastic.
need to be careful as any wrong move will result in the entire Command unit needing to be replaced.
Found this from an e class thread on the same issue, I think this is what we are dealing with, I don’t think anything should be sprayed in there:
The "Volume" knob is not a traditional potentiometer "volume control." The control in these systems is an optical encoder, a digital device. As such, it is not likely to be even remotely user-serviceable. Yes, there may be some fixes out there (similar to those for the Comand knob on the console), but this is not an old-fashioned wire-based component. It is a device with a precision control with a lot of attendant electronics to make it work.
My guess is that Maybe you can get that part of the Comand system and switch it out, but otherwise this will be a costly one to fix.
My guess is that Maybe you can get that part of the Comand system and switch it out, but otherwise this will be a costly one to fix.
Might be a good Junkyard opportunity to fix, you said we can pull the volume knob straight off, rather than replacing entire radio unit — maybe hit local junk yard and grab 1 or 2 volume knobs and see if one works correctly after purchasing it from junkyard.
Might be a good Junkyard opportunity to fix, you said we can pull the volume knob straight off, rather than replacing entire radio unit — maybe hit local junk yard and grab 1 or 2 volume knobs and see if one works correctly after purchasing it from junkyard.
It’s not the knob itself. It’s the actual radio. The knob is perfectly fine.
There is no brass pieces on the knob, you can easily remove the volume knob and power button by just gently pulling and push it back in snap it back into place the same way.
I have a ‘14 cls550 and the radio volume knob is stuck and no longer rotates. Does anyone know if this knob can simply be removed to clean and pushed back into place?
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