Hello,
My power seat (w/ memory) in my 940 wagon doesn't work. I've replaced the computer and switch (twice, the latest time w/ a car that had a working power seat when I removed them, for sure) but that didn't fix the problem. Any other ideas? Last time I checked, the fuses were goood (i even replaced them to be doubly sure).

Thanks a lot!

Dear xluke,

Good p.m. and may this find you well. Does the seat not move at all? If there is indeed no movement - and the computer and switch are properly installed - then:
(a) someone has disconnected the seat from the wiring harness. The seat connector is grey and is found under the plastic cap at the front door-side corner of the seat. If the connectors are together, then
(b) one or both wires - red or black/white (+) and black (-) have been cut or disconnected elsewhere. Trace both wires backward. They run under the driver's footwell side panel (that beside the front center console).

If the seat moves a little, then something is jamming the track, or the drive cable(s) have become worn and/or dislodged. See the FAQs under SITE FEATURES for fixing faulty drive cables.

Hope this helps.

Yours faithfully,

spook

Dear Spook,
Thanks for your reply!

The wireing harness (grey connector) is still connected and is getting power (~12v).

There is no movement, nor noise, or any indication of an attempt at movement at all.

Is there a wiring diagram available for these seats? Any other ideas?

Thanks again!

Dear xluke,

Good p.m. and hope this finds you well. The problem can be:
(a) a dirty switch (spilled drink, etc.)
(b) a failed main relay inside the seat computer
(c) a broken wire in the harness from seat corner to computer, or from switch to computer, or a corroded connector.

If the main relay fails, the seat will not move. At all. You can check this. Remove the computer from under the seat and open it up (plastic lugs on the side of the case ease access). Check to see if 12 volts is reaching the computer. You'll see the main relay (it is bigger than the others). If you apply 12 volts, and push the relay closed with a plastic probe - and the seat works - then you know the relay has failed. You need a new seat computer. If 12 volts is not reaching the computer, when you move the seat switch(es), then the switch(es) has/have failed.

I realize you've swopped out the switches and computer, twice. These things are pretty simply.

There is a Volvo Tech manual covering seats, which covers trouble-shooting. However, points (a) to (c) cover the key issues.

Yours faithfully,

spook

Hi Spook,
Thanks for your replies. I finally got around to doing the test on the computer and here's what happens...

1) If I do nothing, of course nothign works when I press the buttons on the switch.

2) If I push the main relay closed, nothing happens when I press the buttons on the switch

3) If I push the main relay closed, and then press one of the smaller relays closed, the seat moves.

Does this indicate that the switch is bad? Or the seat? Again, it seems strange because I've swapped the switch 3! times.

Well, I'm going back out there to play.

Thanks again,
xluke

Hello again,
Good news! Using your advice I was able to fix the power seats. Here was the problem:

As it turns out, everytime I removed a switch I was pulling the wiring harness slightly out of the connector inside the switch. This occured because instead of removing the torx bolt that is difficult to access on the front of the panel which houses the switch (and the little storage tray) I would just remove the rear torx bolt and spin the assembly forward to access the torx bolts which retained the switch. During this spinning, I was pulling away the wires.

Oh, what a fool I am. Shortcuts are usually a bad idea!

Thanks again,
xluke