Window Lifts

Debugging Electric Window Lifts on a Volvo 240

Q. Patrick Lum

One of my new staff up here has a 83 240. Its rear windows don't work. Front windows used to work, now don't. This happened to my rears on my 260 before. The fix was simple. I believe their switch contacts have been cleaned. The other fix is...?

A. Cam Finnigan

I have never been fortunate (unfortunate) enough to have a 200 with windows, so have never experienced difficulties as such. However, let me say that with any problem on those cars, the very first thing you need to do is check the fuse block. Fuse problems plague those cars due mainly to the metallurgy of the metals used in the holder and/or fuses. The quick solution is to rotate the affected fuses in their holders to see if that cures the problem. This is a temporary fix. A good approach is to disconnect the battery, remove all the fuses, clean all fuses and sockets with a small wire brush or abrasive paper. A good approach is to coat the fuse ends with a protectant such as that used for aluminium conductors.

I have included a diagram of the window electrical system (sorry about the poor quality). It's pretty straightforward. Given how few parts there are, it should be simple to trace. The index does not include these components but looks as though they are as follows. Top are five driver's switches (light yellow): rear one side, rear other side, disable rear windows, passenger side front, driver window. The three remote switches (light blue) are in a row near the bottom. The motors (green) are shown as "M". Item 126 (purple) appears to be a relay that enables power to the whole system. One line BL-Y comes from the ignition switch and the other most likely should be unswitched but possibly fused. Obviously, this needs to be verified.

Click for Full-Sized DiagramFull Sized Diagram
Here's how it works. The remote switches (i.e. at the rear of the car, highlighted in light blue) normally just connect the motor (in green) through to the driver's switch (in light yellow) on two wires. Both of these wires are normally connected to ground by the driver's switches. Pressing the driver's switch for the rear window removes ground and applies +12 V to one wire or the other depending on the direction required. The switches at the remote (rear) location operate by also removing ground from one of the wires and applying +12 V to it from the 1.5 Y wire from the rear "disable" switch at the driver's position.

If the rear windows don't work, there are other questions like which switch (front or rear) doesn't work, or both? Do the windows go up but not down on one of the switches? The switches have many contacts so a failure may not result in total failure.

For the rear windows, here is a typical debug scenario. First, fashion a test light using a bulb such as a 22 W brake light. Attach one lead to a 12 V source. Test the light by touching the other lead to a good ground on the car; the light should come on. Go to the rear actuator motor and touch the test light lead alternately to each of the two contacts. The lamp should light brightly in both cases, indicating that both terminals of the motor are correctly grounded. If one terminal or the other (or both) does not produce a strong illumination of the test light, then this test should be repeated going to the rear switch, the harness connecting the rear to driver's switch, and finally to the black ground wire that will be attached to a grounding point on the chassis. In each case the lamp should light brightly.

Next, turn on the ignition key and ensure the rear window switches are enabled. Move the test lamp's fixed lead from +12 volt to ground. Connect the free end to the yellow wire going into the rear switches. It should light. If it doesn't, check again at the enable switch at the driver's position, both red and yellow wire. If the red has voltage and yellow doesn't, suspect the switch. If the red wire does not have power, then there is a fault in the supply and the relay should be checked next. Pressing the rear window switch should place 12 V across the motor, ground on one side, 12 V on the other.

The front switches are tested in the same manner, the main difference being a red wire supplying 12 volts instead of a yellow wire.

Given that the windows did not all fail simultaneously, it rules out just the fuse(s). Nevertheless, that is a good place to start.