Power seat switch refurbishment 1998-2004 C70

[stonesfan68]

Volvo no longer makes the front seat switches for the 1998-2004 C70. As near as I can tell it is the same part for the 1998-2000 S70, V70 and V70XC.

Front Left: 9472715 / 9472434
Front Right: 9472716

My driver’s seat switch started to fail and when I discovered it was no longer available, I decided to take it apart and see if I could fix it.

Take a look at the underside of the seat. You’ll see that the switch is connected to a black control module that has two wiring harness connected to it. Remove the green harness by pressing the tab at the bottom of the connector up.

Next, remove the switch and plastic trim from the seat. There’s a captive T25 Torx screw in the side of the plastic cover. Loosen it and then rotate the assembly towards the front of the car. The plastic trim piece is held on by a clip. Pull up and the trim piece will come free.

The switch separates from the trim piece by removing three T25 Torx screws. There is also a zip tie that needs to be cut.

Once you have the switch free inspect it for obvious faults including corrosion (“green crusties”) and broken traces on the printed circuit board (PCB). My PCB had some corrosion on the back side.

Leave the switch face down on a clean towel. Remove the seven T8 Torx screws and gently lift up the PCB out of the plastic case.

There is a really small spring under each of the four memory buttons.

I used a small magnetic screw driver to remove the four springs from the plastic. Put the screws and springs aside- I recommend using a small plastic bag.

As you can see, there are four individual switches- each covered with a plastic cap. I used a pick tool to pry up on the cap and a small screwdriver to further separate the cap from the switch. Don’t pry against the PCB!

Once the caps are removed check the switches for corrosion. The single switch that was wasn’t working in my car had some corrosion between the spring and contacts.

I blasted both sides of the PCB with electronic contact cleaner (made by CRC or WD40 Specialist).

I made a paste of out baking soda a distilled water and applied the paste over the corroded components. I waited for about ten minutes and then washed off the paste. I had to repeat this procedure a couple of times. Some emery cloth or fine sandpaper would help, too. After rinsing the paste off I then blasted the PCB with the contact cleaner.

Use a multimeter or continuity tester to test each of the switches. There should be a clear “click” as you push the switch in either direction. It is a bit tricky to do by yourself so try and recruit a helper to hold one of the leads against a switch contact.

I then used a product called DeoxIT G-5 to lightly coat the metal switches, springs and PCB board. The DeoxIT cleans corrosion, enhances electrical contacts and protects the contacts from oxidation.

Then put the caps back on to the switches. Note the arch of the switch bases- the caps can go on one way.

Using a small screwdriver, pry apart the connector housing. Check the terminals for corrosion and clean them accordingly.

At this point I took the cleaned switch assembly out to the car, plugged it in and checked that everything was working properly. Success!

Thoroughly clean the plastic housing with dish soap and a gentle toothbrush. Dry the plastic off and let it air dry for a bit.

Then, put the small springs back into their holes and then place the PCB back into the housing, routing the cable as required. The PCB only fits one way. Screw the seven T8 Torx screws down being careful not to overtighten them.

Put the switch assembly back into the plastic trim making sure to use a new zip tie to attach the cable to the trim piece. Install the trim piece back into the seat, plug the connector into the seat control module and then pat yourself on the back for saving yourself some money.

I hope that this helps some people.

[scot850]

Thanks for taking the time to write this up for all the forum users. Really appreciate the detail!

Neil.

[jreed]

Great write up with super sharp photos. This makes me want to take mine apart! Thanks

[abscate]

The 1998-2000 s70 v70 is slightly different. Electrically it will function but the mounting is different.

[MoVolvos]

.
Houston, we had a problem. Nice work!
.