Do It Yourself Auto Repair: Common Electric Car Window Repairs

At home power window repairs explained. A step by step diagnostic procedure to fixing an inoperative window.

Most power window systems are common and can be repaired at home with a little knowledge. The basic problem with electrical systems is power. An electric motor can't function without it, yet some people run out and replace the motor without doing any testing at all. Then they get mad when they find that it was an easily replaceable switch or fuse in the first place. The easy items, that's the place to start.

First thing: Check the fuse.

If the fuse is in good condition the next step is to check for power to the fuse using an inexpensive 12-volt test light. These very helpful tools can be bought at any automotive parts store and some super-center retailers.

Power to the fuse comes from the ignition switch and is activated by turning the key to the 'On' position. This makes the car more secure from break-ins with a long stick or coat hanger. It also prevents kids from draining the battery by playing with them. The key has to be in the 'On' position to check for power at the fuse. If the fuse has no power with the key on, track the wire back to the steering column to find the right one for that fuse. Wiring diagrams come in handy at this point and are easily deciphered.

Power in, no power out. That narrows the problem down to one component - the ignition switch. Often times, it's best to have a professional replace the ignition switch. If the switch isn't adjusted properly a mess of other problems will arise. If the car has air bags, replacement at home isn't an option. If the fuse does have power, the next step is the door switch. Most switches are held in place with barbs and simply pop out with a small screwdriver. Others are held in place with small screws.

Pull the door switch out of the panel. With the wires still connected the switch should have one or more powered leads depending on make and model. If there is no power, or it's not certain that the test is being done right, a 'known good' switch from another door (with the exception of the drivers' master switch) can be swapped with the suspect one. If the window still doesn't function the best place to look is in the doorjamb for a damaged wire.

The wires run through the doorjamb in order to get from the body to the door units. Several years of opening and closing the doors cause the wires to get brittle and break after being kinked and straightened. This is a common problem with the driver's door, especially.

If the switch is determined to be good, and powered up, the next stop is at the power window motor itself. The entire door panel will have to be removed to access the window motor. The motors' plug will have 2 wires coming from it. Back probe the plug as it sits, connected to the motor, and cycle the door switch back and forth.

One wire will light with the switch in the 'Up' position and the other wire will light in the Down'. In the opposite direction, the power becomes a ground. Attaching the ground clip of the 12-volt test light to a power source turns the probe end into a 12-volt ground tester. If the wires power up on queue, then the motor itself 'could be' at fault. Make sure the window itself moves up and down freely with the motor unattached. The motor is only so strong. A binding slide can keep it from moving or burn up the new motor very quickly.

Replacing a motor consists of removing the linkages, spring and motor as an assembly. The spring assembly is extremely dangerous and should be handled with the utmost care. If the spring were to be released accidentally, the two scissor-like arms that are attached will close at an extremely fast rate with enough force to cut off a finger or two.

The safest way to dismount the motor from the carriage is to place the linkage arms into a bench-mounted vice and secure it tightly. This will keep the arms in place and replacing the motor becomes much easier because the lateral force of the spring on the motor is negated by the vice.

The power window circuit boils down to just those few items in most cases. In recent years, manufacturers have started using a module assembly inside the door. Power is run through a single wire into the door module instead of running individual wires for every component. That module powers everything from the windows to the door locks to the heated power mirrors with the turn indicator.

© High Speed Ventures 2011