Troubleshooting: Power Windows

Automotive master window switch.

This is an EXCEPT question about a power window that moves slowly and the switch must be pressed several times to move the window up or down. An open in the window switch or anywhere in the circuit will result in no operation of the power window. It also reminds us that a blown fuse creates an open circuit until it is replaced. A self-resetting circuit breaker resets itself. This fact omits an open window switch or fuse as a possible cause, because the window would not move with an open circuit.

Automotive power window motor and regulator.

This problem could be electrical or mechanical. Self-resetting circuit breakers are often used in place of fuses in window circuits because they actually serve two purposes. They not only protect the circuit from overload, but also open the circuit when the window seats into the window frame or the base of its travel. When there is a circuit overload caused by a faulty gasket, motor, or regulator the circuit breaker opens from the excessive current, cools and allows the motor to temporarily move the window just a little bit until the breaker heats up and opens again. This dragging window could also be caused by a weak motor, binding window run, or a misaligned window regulator.

Window gaskets: The window fits snugly into the window gasket and if anything interferes with its movement or if there’s a kink or bend in the gasket, the window will drag. Silicone is often used to make a window run or weather strip more pliable.

Circuit breakers: Some circuit breakers need to be manually reset by removing them from the power source or pressing a button. Many other circuit breakers are self-resetting. Today’s circuit breakers are solid state "ECB’s". These circuit breakers increase resistance as they heat from excessive current. They can heat quickly and prevent the window from operating. Circuit breakers may control more than one window at a time. Both driver’s side window and the sun roof may be on one circuit breaker while the passenger’s side window on the other. It's important to have a schematic if you 're not familiar with the circuit.

Fuses: When a fuse is overloaded meaning too much current is passed through, the element will melt creating an open. They do not reset like circuit breakers and must be replaced to complete the circuit. It’s important to rule out any component or short circuit that may be causing the fuse to blow. Sometimes fuses just blow from a temporary overload caused by icy windows and such. This rules out the fuse as a possible cause because the window does move a little, a blown fuse would result in no operation.