Driver's power seat died and resurrected
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    1. #1

      Driver's power seat died and resurrected

      My daughter's driver's power seat started dying a year or so ago. It was intermittent at first. Whether it worked or not generally seemed weather dependent. It seemed least likely to work on chilly damp mornings but eventually it quit working altogether.

      The way it was acting made me initially think that I had a relay going out. But the owners manual fuse box diagrams showed me that there was no relay. The fuse was good and had power even when the seat didn't work. I replaced it anyway just in case there was some oxidation causing intermittent contact - no luck.

      Since the preceding didn't help and it first started acting up shortly before I was to have the timing belt and top motor mount service done, I had the dealer look at it while they had it and give me a price. They said the seat module had to be replaced and that it would be another $400+. I politely declined.

      When the seat stopped working entirely, it fortunately did so in a relatively comfortable position, which placed its repair on the bottom of the todo list. However, I would occasionally, without much success, do a little searching on various Volvo forums.

      When the dealer said "module" I was thinking big electrical box mounted under the seat. I've seen these in other vehicles. There is no such thing in a 2006-13 C70. I even double checked by downloading the electrical systems PDF for the p1 volvos I found online.

      Instead of big separate module, I should have been thinking "seat switches". The traditional module function is merged into the seat switches' housing in a circuit board - lets call the whole unit the seat switch/module unit.

      After discovering this, I figured that the dealer thought that it sounded better say "we have to replace the seat module and unfortunately that's going to be $400" instead of "your switches on the side of the seat are bad - 400 bucks".

      Enough rambling... Let's get to it: I pulled the seat switch/module out (to get it, remove one torx screw out of the front inside portion of the plastic seat side cover that goes over the switches. Then slide the cover forward to free it. At this point, you can remove the 4 or 5 torx screws that hold the switch/module to the inside of the cover. Now you can squeeze the tabs to release the 2 electrical connectors). I then removed the several small Phillips screws on the back of the switch/module housing and closely inspected both sides of the circuit board. I found a corroded electrical doodad, which I'll call a "chip".

      There should be 2 pics attached below. One shows the switch/module. The second shows one side of the circuit board within. I put a red arrow on that picture pointing at the corroded chip - it was a greenish sort of corrosion similar to the stuff that forms on a battery.

      I didn't think it would help but I cleaned the chip with alcohol and swabs. I was right: it didn't help. When I put the old switch back in I also checked to make sure power was going to the unit. Since there was power and it didn't work, I ordered a new switch/module.

      The new switch/module unit was $130 plus $20 shipping: so, $150. It took me no more than 3 minutes to remove and replace. So the dealer was going the charge me $400 for a part they would have paid no more than half of what I paid and 3 minutes of labor. They should be ashamed.

      NOTE: A switch unit from an p1 S40 or V50 may not work in a p1 C70. When I did my search, the C70 modules only listed compatibility with the C30. While the others look the same they may have different programming. I did not cross the parts numbers but I looked at several suppliers.




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    3. #2
      Junior Member Olstyle's Avatar
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      If that chip really is the only concern you could have just replaced that:
      http://www.infineon.com/cms/en/produ...132fa7814600b7
      It's just a "smart MOSFET", so there is no programming missing.
      Of course the new unit is the safer option, but at least out of curiosity I'd still try the solder option.

      Was there a casket at the lid of the module? Otherwise my bet for the cause of the defect would be water from e.g. cleaning the seats too vigorously.
      Last edited by Olstyle; 05-04-2017 at 12:00 AM.
      C70 I 2.0 -> C70 II T5 -> the Moon?

    4. #3
      That was the only issue I could see. I had on 3 pair of readers to find it. I'm not sure if repairing it is in my skill or vision set. I replaced some caps in a flat screen tv one time but the switch unit is a much more delicate job. Before your post I didn't even know what the chip was called or how I could find one. But I would certainly like to try. Or if I knew an electronics guy take or send it to him.

      It appears to me that water can easily enter the unit.

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    6. #4
      Junior Member Olstyle's Avatar
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      The board has the names of the bigger chips on it. That's actually quite nice of the manufacturer.
      C70 I 2.0 -> C70 II T5 -> the Moon?

    7. #5
      Junior Member regtor's Avatar
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      Great writeup, thanks for posting. What's the Volvo part number of the seat module/switch? Also, was that price new or used?
      regtor
      2011 C70 T5 electric silver metallic/cranberry
      dynamic, multimedia, climate & convenience packages
      blis, sport pedals, oem front strut bar, elevate rear sway bar
      polestar+ performance upgrade

    8. #6
      It was new and in the blue volvo parts box (inside of its shipping box). It was from Royal South Mazda/Volvo in Bloomington IN. The part number was 30659543. I use ebay often and that just happened to be one of two or three from different dealers at that particular price. There were other sellers priced higher. I've never ordered parts from them before. I just happened to choose that dealer. I ordered it Sunday evening and it was in my garage yesterday, Wednesday, when I got home from work. I thought that was pretty amazing from Indiana to South Mississippi.
      Last edited by rodneygt; 05-04-2017 at 04:23 PM.

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