Power Windows and Door Locks

A power window uses a small but powerful electric motor connected to a regulator mechanism that raises and lowers the glass along a track. The motor receives power and ground through the window switch. The switch reverses polarity to change motor direction — send power one direction and the window goes up, reverse it and the window goes down. On vehicles with auto-up and auto-down, the BCM controls the window through a module in the door that monitors motor current to detect pinch conditions and reverses the window if an obstruction is detected.

A window that moves slowly or stops partway up usually has one of three causes. A worn window motor that no longer produces enough torque — voltage drop test the motor circuit while operating. A binding window track — the channel the glass rides in is dirty, corroded, or damaged. Lubricate the tracks with silicone spray first. A failed regulator where the cable has frayed or the gear mechanism is worn. If the motor runs but the glass does not move — the regulator has failed mechanically while the motor is still good.

Door lock actuators are small motors or solenoids inside the door that mechanically move the lock rod. Each door has its own actuator. A door lock that does not respond to the key fob or the interior switch but works manually with the interior lock knob has a failed actuator or a wiring fault to the actuator. If multiple doors fail simultaneously, check the BCM and the lock circuit fuse before condemning individual actuators.