You roll down the window on your Mercedes Benz ML430 to place an order at a fast food drive-thru or to get some fresh air, and the window won't budge. It groans and vibrates a bit. Afterwards, it doesn't respond at all. This calls for a power window motor gone bad. Fortunately, troubleshooting it is pretty much a straightforward task. Detecting a failure in the window motor only requires simple and basic tools. In most cases, you will find problems with the window switch, gears, and relays. Here are some of the signs that point which part is exactly going bad.
When you hear the window clunk and feel a strong vibration inside the door panel, there's a big chance that the motor is experiencing difficulties with its parts such as the gears and the rotor. These components are responsible for moving the window glass up and down. Through time and physical wear and tear, these parts could get loose, or worse, experience deterioration and fall apart altogether. You need a specialist to rebuild a broken motor. However, if the damage is too much beyond restoration, replacement is needed. Or else, you won't be able to use the windows any more.
If you notice there's this faint whirring sound whenever you use the windows. That's because the gears and the rotor move at relatively high speeds in order to ensure smoothness in the ascending and descending of the glass. If there's no whirring sound, there's a possibility that the motor is not getting enough energy in order for it to function well. This is evident when the windows are not responding to the switch. Try and see if there's a blown fuse of errant wiring connection. These could be the cause of the motor's lack of power.
There's a certain speed of glass window movement that is quite noticeable once you've gotten well acquainted of your vehicle. Any deviation with this may indicate that the components inside the door panel that operate the window don't have good lubrication. Once this happens, the motor is sure to experience resistance and it will have to push harder. If this happens frequently, you might risk damaging the motor.