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Mercedes Benz 420SEL Window Switch

Diagnosing a Faulty Mercedes Benz 420SEL Window Switch

The window switch is one of the most convenient components in any vehicle because it allows you to lower or raise the glass windows with just the use of your fingertip. However, it's quite inevitable even for this little guy to become faulty in a matter of time. To avoid having troubles with controlling the windows of your car, here are some troubleshooting tips to help you diagnose if it's broken.

Humming sound

Push the window switch to lower the glass window. If it doesn't go down, but you hear humming sounds, then there's a problem with the gears or the motor. Replacing these would entail you to take out the door panel so that you can see which one is not working. Use a test light to check if the motor has power and if the window gears have broken teeth.

Used-up regulator

Since you've already taken out the door panel when you checked the motor and the gears, you might as well check up on the regulator. Take a good look at the window regulator, which secures the window to the frame. If it's worn, it won't be able to work the way it should. You'll have to replace this part in order to easily control the windows using the Mercedes Benz 420SEL window switch.

No power

Using a test light, inspect the main circuit relay to check if there's voltage coming from it. If there's voltage, there's a short in the wire that's coming from the main wire, which provides power to the switches. If there's none at all, then inspect the main wire to know if there's voltage in the relay switch. If that's the case, then you must have the wire replaced. Otherwise, the problem with the window switch is caused by a short in the wire from the fuse to the relay.

Blown fuse

With your key in the ignition, turn it to on and lower all the windows on your vehicle. If none of them is working, then the problem is caused by a worn fuse. Look for the fuse box and check if the fuse is blown. Replace it with a new one so that you can still operate the glass windows on your ride.

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Mercedes Benz 420SEL Window Switch Available Years

  • Mercedes Benz 420sel Window Switch Proper Maintenance 27 February 2013

    The Mercedes Benz 420SEL window switch is a perk on your vehicle that gives you the luxury to control the glass windows anytime you want to. Replacing this with a new one when it gets busted can be a little bit complicated because of the different wirings that you'll have to deal with. Instead, you can make it last longer by following some of these maintenance tips.


    Cleaning tips:

    Know when it is time to clean the window switch.


    When you feel like the window switch connection is becoming problematic, it could mean that it's pretty dirty and it should be cleaned. It can cause the glass windows to hesitate or not go up at all. You'll also have a hard time lowering it down once it gets stuck up. This is the time that the window switch should be cleaned and sanitized.


    Look for the culprit.


    Check your manual to know where to find the fuse box. Inspect this and check if it's blown or dirty. If it is, you'll have to replace it as soon as possible if you want to continue to have a functioning window switch. Also check the connections for broken wires that might need to be replaced.


    Make sure that your hands are clean before using the window switch.


    Oftentimes, you go to a drive-thru restaurant and eat your snacks inside the vehicle. While eating French fries or a burger and you decide to lower the windows without sanitizing your hands, it can cause grease, crumbs, salt, or other food particles to build up around the window switch. It can contribute to poor contact because it can enter the nooks and crannies of the switch. The best thing to do is to make sure that you clean your hands before you use the window switch.


    Other tips:

    Whenever you clean the inside of your car, make sure to include the door panel and carefully freshen up the window switch. If you happen to eat inside your vehicle and you decide to lower the window, make sure to clean the switch right away to avoid any debris or droppings to build up.