What is the reason why the left rear door of the Focus cannot be locked and the window cannot be raised or lowered?
4 Answers
The reason why the left rear door of the Focus cannot be locked and the window cannot be raised or lowered is due to a damaged window regulator motor. Precautions for using the window: Clean the window glass: Dirty window glass not only affects appearance and visibility but also interferes with the opening and closing of the power window. To prevent rainwater from entering the car, there is a rubber strip attached to the upper part of the window frame, which is also the area that frequently contacts the glass. Excessive dirt on the glass increases friction with the rubber strip, thereby affecting the window's operation, so it is essential to keep the glass clean. Lubricate the lifting mechanism: The main reason for the power window switch not operating smoothly is often the depletion of lubricating oil inside the door's lifting mechanism. Therefore, the lifting mechanism should be regularly lubricated. The lubrication method is as follows: First, remove the inner cover, peel off the waterproof plastic sheet below, remove the hidden screws, and detach the quick-action switch; then spray grease inside the window gear, moving it up and down while spraying to ensure even the finest parts are lubricated. Check the rubber supports: After lubricating the lifting mechanism, inspect the rubber parts supporting both ends of the glass. If the sliding condition of the glass is poor, apply a rubber protector.
I've been repairing cars for many years. The common causes for the left rear door of a Focus not locking and the window not working are often due to a faulty door control module. That little box manages the locking and window circuit. Once it gets short-circuited from water damage or wears out, everything stops. First, open the fuse box to check if the door circuit fuse is blown, and try replacing it with a new one. Then inspect the switch buttons; if there's no response when pressed, it might be a stuck window regulator motor or loose wiring. Water often accumulates inside the door, especially after rain, corroding the wiring. If not handled properly, it can lead to more issues. Removing the door panel yourself is risky, so it's recommended to take the car to a professional shop to test the module's condition with specialized equipment—it's faster and safer. When parking, avoid waterlogged areas and regularly check the door seals to prevent water ingress.
My Ford Focus had this annoying issue before - the left rear door wouldn't lock no matter how many times I pressed the button, and the window wouldn't move either, which was really frustrating. I checked the manual and tried fixing it myself, suspecting either a shared fuse had blown or the window switch was burnt out. After replacing the switch, the window could roll up and down, but the lock still didn't work. Turned out the lock motor was faulty, and the repair shop had to replace the entire assembly before it was fixed. Similar cases are mostly caused by circuit shorts or aging control components, especially with the Focus's door design that tends to accumulate dust and water. It cost me some money, but getting it fixed promptly gave me peace of mind. I'd advise checking if your doors stay dry after rain to prevent corrosion. When driving with friends, safety comes first - don't delay dealing with such issues for too long.
I have experience in circuit design. The common root cause of the left rear door failure in a Focus lies in the integrated circuit system. The door lock and window lifter share a control unit, and the fault point could be internal component failure or poor signal line contact. Simply check if the fuse is blown—that's overload protection. Aging wires causing short circuits can also lead to dual failures. Water ingress is the main culprit, corroding electronic components. It's recommended to use a multimeter to test the power line and ground terminal. Replacing the unit module is the only permanent fix.
