1. Switch: When you press the window switch (either the master switch on the driver's door or individual switches on other doors), a small electrical current flows.
2. Window Regulator Motor: This current activates the electric motor located within the door. This motor is responsible for the up-and-down motion of the window.
3. Window Regulator: The motor is connected to a gear system (part of the window regulator) that translates the rotational motion of the motor into linear movement. This regulator uses a cable or a series of rollers to move the window glass up and down.
4. Window Glass: The window glass is guided by channels within the door. These channels keep the glass aligned and prevent it from rattling or binding.
5. Wiring Harness: A wiring harness connects the switch, motor, and any other components (like a relay, in some systems) together.
If the motor still works, can you replace plastic parts?
Absolutely. The plastic parts that are most likely to fail in a power window system are:
* Window Regulator: This is the most common part to break. The plastic gears, clips, and possibly the cable can wear out or break, rendering the window inoperable even if the motor is fine. You can replace the entire regulator assembly, which is usually available from auto parts stores.
* Window Tracks/Channels: The plastic channels that guide the window can become worn, cracked, or broken. These are often replaceable separately.
* Switch Housing: The plastic casing around the power window switch can crack or break. This is typically a separate replacement part from the switch itself.
* Clips and retainers: Many small plastic clips and retainers hold various components together. These are often inexpensive and replaceable.
Before replacing parts:
* Diagnose the problem: Make sure the motor is actually working. If the window doesn't move at all, even with a good switch, the problem is likely further down the line (regulator, wiring, fuse). If it makes a clicking sound, the motor might be weak or failing.
* Check the fuse: Verify the power window fuse hasn't blown. Your owner's manual will tell you where to find the fuse box and which fuse is responsible.
* Check the wiring: Inspect the wiring harness for any damaged or broken wires.
If you are mechanically inclined, replacing these parts is usually a DIY job, though it can be fiddly. YouTube videos can be very helpful in guiding you through the process specific to your 1999 Jeep Cherokee Sport. If you're uncomfortable working on cars, it's best to take it to a mechanic.
