I finally fixed the electrical problems in the tailgate of my Subaru Impreza. Four wires were broken where they pass from the frame of the car to the frame of the tailgate. I tried to fix the problem a while ago, but couldn’t locate the source. My multimeter gave correct readings, but nothing worked. The wires must have only been partially broken then. This time it didn’t take long to find the problem. There is almost no slack in the wires, so reconnecting them took a while. Now the electric lock works again. The rear defroster should work too. The wiper motor is still intermittent. It is probably run by one of the lines I haven’t fixed yet. Last summer, I had a similar problem with the rear washer fluid line. I was able to splice it back together.
Putting wires in a place that they will bend the same way many times is a problem. With car doors it isn’t too bad because the angle they bend through is fairly small. With a tailgate the angle is much larger, making the wires and hoses ore more likely to break. This would be a good place for a couple connectors and a short length of heavier cable. Since this problem isn’t likely to happen for the first owner of a car, the design probably won’t be changed.