QuestionQUESTION: My car recently developed a fault where the passenger side, and rear window lifts have stopped working. The drivers side works perfectly but nothing on the others. I have looked at the wiring diagram but cannot trace where the wires go to when after they leave the center console. My Haynes manual is of little use in this respect as it points to a 'circuit earthed' problem but does not elaborate in this. Hope you can help - thanks!
ANSWER: Jim, the window lift motors are just a two wire motors and the switch just reverses the polarity for the motor to run up or down. So all you need to do is check to see that the switches have power and do reverse the polarity of the two wires going to the motors and that the ground wire is grounded at the appropriate time. You can test the motor by use of a power and a ground test lead to the two motor leads (disconnected from the harness). Some cars had a child safety lock out switch so test that too if your car has one.
Howard
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QUESTION: Hi Howard, and thanks for your response. As you say, the switches just perform an inversion of the 12v to operate the windows up and down, and I can confirm that they all work once an earth is applied to the appropriate pin on each switch. However, I was interested to know where the original wires end up in the car to actually fix the problem, rather than just add more wires under the console. The Haynes manual wiring diagram just shows the earth wires as a common rail, and in electrical terms this is probably true, but physically it involves a seperate earth for each switch which comes out of the loom in the center console. If possible, I'd like to know where the other end of these wires end up so I can test them, or see if its a loose connection in a terminal as is suggested in the Haynes diagram.
Thanks again!
AnswerJim, my diagram shows one common ground wire and one power wire. According to my diagram if the drivers switch operates then the power and ground for the system is ok, because they all share the same power wire and ground wire. If only the other switches are not working then the power or the ground is lost between the switches not in the harness.
The power and ground just goes to the drivers switch and then on to all the other switches.
If you can jumper power and grounds at the switch to operate a passenger window then the problem is right there in the switch area. If you can't operate a window at the switch wiring then the problem is in the harness between the switches and the doors.
My diagram shows only one ground wire (green that connects to black) and if it fails the drivers window will not operate.
So it is no use looking for the source of the ground wire because we know for sure the ground wire is good because the drivers window operates.
Since all of the passenger windows have failed all you need to do is test the red w/purple tracer wire and the green w/purple tracer wire that runs from the driver's switch to the front passenger's switch at each switch to see where the connection is lost. (Or the switches are bad which is a very common problem on all of the XJ cars.) The good thing is that the switches can be taken apart easily and clean the contacts and it works again for a year or two.
Howard
