No Sound – Common Navigation/Comand/Radio Problems
- Head Unit / Radio stuck on Mercedes-Benz logo
- It turns on and then off
- Shuts off randomly
- COMMAND will freeze
- The radio powers on, but there is no sound
- Audio Gateway (AGW) drains the car battery
- The radio panel doesn’t turn on. (Hint: Check fuses.)
Most Common Solution
The first thing you should try is to do a soft reset of the COMAND unit. To do a reset, you will need to remove the fuses for at least 10 min for these systems:
- COMAND/ NAV / DVD Player / Radio
- CD Changer
- Voice Unit, if equipped
- Audio Gateway AGW
Removing the fuses for these systems will force the command unit to perform a rest. This will generally fix the problem. There is a chance that the symptoms may return. If you have the same problem after a few weeks, check with your Mercedes-Benz dealer to see if they have any updates for your comand / navigation unit.
How to do a soft reset of the COMAND / NAV Radio System
Here are instructions on resetting the audio/radio/command/cd changer system on an E-Class W211. If you have a different Mercedes-Benz model, different fuse numbers will be assigned to your command, radio, CD changer, and audio gateway. Look up the fuse chart for your model to identify the fuses for these components.
Locate the fuse box on the side of the dash on the driver’s side.
Remove the fuse box cover.
Locate fuses 26 and 28. Remove both fuses.
Locate the fuse box on the rear. Start by opening the trunk. The fuse box is located on the left side of the trunk.
Remove fuse #6
The fuse number will be different depending on the model of Mercedes-Benz that you have. The fuse numbers provided here apply to E-Class W211 2003-2008
Remove the key from the ignition and let the car stay off for at least 15 min.
Troubleshoot fiber optics
If removing the fuses does not solve your problem, the next step would be to troubleshoot the fiber-optic loop. Mercedes-Benz uses fiber optic cables to transmit the sound signal between the different units. Fiber optics provide faster transfer rates and better sound quality. All the audio-related systems in the car are connected via the fiber optic cable in series, forming a ring or a loop. The signal will travel through all the components and return to the same component if required.
Components that are part of the fiber optic ring are:
- Head Unit/Comand/Navigation/DVD/Radio Head unit Audio 50 APS
- CD Changer
- Communication platform
- Voice recognition module
- Audio Gateway (can not bypass)
When one of these components (in yellow) goes down, your COMAND will stop functioning. Let’s say your CD changer fails. You will not be able to use the COMAND at all. The system will turn on and then off or will turn on, but you will have no sound.
The COMAND will typically power on and then go off, get stuck, have no sound, or not power on. If this happens, do not automatically assume that the issue is the head unit.
To solve this problem, you must figure out which component is defective. You can bypass the different components until you find the problem. You will need a Fiber Optic Loop Adapter to bypass the system, one at a time until your COMAND system works.
If you bypass a component and the problem is not solved, try the next component on the list. The Audio Gateway AGW can also be defective. That is the brains of the Mercedes-Benz COMAND system; therefore, you can not bypass it. You will need to replace the whole unit.