1994 Mercedes-Benz S420 Window Switch Replacement Cost

When servicing window assemblies, the window switches are recommended to saw changed. The switch's hold the weight of the vehicle, and allow the front wheels to turn more easily.

When the ignition switch is placed in the run, or accessory position, the window switches on the door are activated, normally through a power relay. Pressing the switch pulls electricity from the battery, through the relay and fuse block, and into the window motor. The is what causes the window to rise and fall on command.

When a switch can not make contact and close the circuit, the window cannot be raised and lowered. If the switch on the driver's door will not raise or lower the window in question, but the switch on the corresponding door works just fine, this is a good indication that there is a switch failure. This works the other way around, as well. If the switch on the door does not cause the window to function, but the driver's switch does, that is an indication of a passenger door window switch failure.

Driving with a window switch is not likely to damage any other components, unless the window switch is constantly rolling one of the windows up or down. If the switch is constantly engaged, the corresponding window motor may become overworked and fail. Also, some vehicles will not turn off all accessories when the engine is off with the key removed, because the window switch is still being pressed. This can lead to security issues, theft, inability to raise or lower the corresponding window, and a dead battery.

Window switches are meant to last the life of the vehicle, based on the amount you are expected by the manufacturer to use it. This is intended, but frequent use, coffee spills, rain water, and dust collection take their tole on window switches. When they fail, which can be at any time, they become unable to transmit signal because of loss of contact. The more harsh their environment, the quicker failure is expected.

Window switches are diagnosed by process of elimination, from most likely, to least likely. The fuses are checked first, then the power at the switch, then power coming from the switch. If the power going to the switch is present, but the power coming from the switch was not present when pressing the button, the switch must be replaced. If the switch sends power, but the window will not go down, the power at the window motor would be checked, to find if the window motor is functional.

When a technician replaces the window switch, they will generally be done in short order, both diagnosing, and replacing the switch. Since the switch must be removed to diagnose, the only thing to be done is pop in the new switch, and click in the armrest. When the technician removes the switch to test the switch and harness, they remove the panel which retains the faulty window switch, and once complete, the panel goes back in after the window switch is attached.

Diagnosing and replacing a window switch is not a long, tedious, or expensive process, so if the shop estimate reflects more than an hour of diagnostic time and labor combined, this should be discussed in detail with the service manager, and possibly taken for a second estimate. If the window switch functions properly, but other components on that circuit are preventing window function, the shop estimate may be considerably higher than expected.

Aftermarket window switches may not match in appearance or function. Automatic window switches may or may not function, and the image of the chip and shape of the switch may be different. When selecting a switch, have a photo of your switch handy, and note whether the switch is for automatic windows.

Replacing the window switch is a good project for anyone. The armrest typically pops off, and the switch usually disconnect from the back of the armrest. You should take it to a professional before prying on something turns to breaking something, or if you would like the problem diagnosed.