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  1. #1
    Join Date
    Dec 2004
    Posts
    8

    Default 2012 X70 Driver's Power Seat not operational. Seat stuck in forward position

    All,

    Looking for some guidance/advice on what to do with my wife's car. It is a 2012 XC70 and the front driver's side seat does not work anymore for the past several weeks. There was a small leak in the above driver's side windshield that let some water drip onto the driver's seat during a heavy rain (towards the front left side of the driver's seat). I think after that the seat didn't work based on recollections from my wife. I plugged in my Volvo ODCII reader and it showed DDM-U020800 "Lost Communication with Power Seat Module. General Failure Information. No Sub type." Based on that code, I thought I need a new power seat module for my 2012 XC70. I also checked the fuse in the fuse compartment (20a) under the glove box for the power seat and its fuse looked fine.

    I got a used 30797728 Driver Seat Module from Ebay (same number as my installed part). I connected it but the seat didn't work and I still got the same code on the Volvo Reader as before. The cleaned the connectors and they all look shiny.

    At this point, I'm not sure where to go. I guess I could have received a bad Ebay part but that seems unlikely. Should I purchase another used one? A new one is around $130 after shipping but if it doesn't fix the problem then I cannot return it since it's an electric piece (from what I gather reading return policies since I will be connecting it to my car).

    Any thoughts. I cannot drive the vehicle as is and that's a problem.

    Thank you in advance.

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  2. #2
    Join Date
    Aug 2017
    Location
    Pleasanton CA USA
    Posts
    368

    Default

    As a first clue, the battery must be disconnected when unplugging and plugging-in a power seat module. When reconnecting the battery, give it 2 minutes in this power-up mode for all the modules to reload software and restart, then start engine and test seat.

    If you go to a Volvo dealer, you're looking at about $200 and having everything working again. This could include downloading the correct software into the seat module.

  3. #3
    Join Date
    May 2012
    Location
    Calgary, Alberta
    Posts
    595

    Default

    I would suspect corrosion in a connector/damaged wiring harness. By the time you noticed a leak it could have been happening for a long time and caused problems. With low voltage CAN (the communication network) it would not take much to stop things from working.

    Try to find wiring diagrams for you car for the seat to check for connectors or start pulling the seat and carpeting to track the wire harness back from the seat.

  4. #4
    Join Date
    Dec 2009
    Location
    GA
    Posts
    1,252

    Default

    Quote Originally Posted by brickson View Post
    water dripped onto the driver's seat (towards the front left side of the driver's seat).

    I checked the fuse (20a) under the glove box for the power seat and its fuse looked fine.

    I got a used 30797728 Driver Seat Module. I connected it but the seat didn't work

    Any thoughts.
    If the seat switch/module got wet it could have been damaged. - I've not done a seat module on the 2008+ cars but the earlier ones (2001-07) needed a software download to make them work. The parts catalog shows software being needed when replacing that part on your car. From experience during a seat module replacement, the seat would move with the NEW module, but needed software to make the memory function.

    I'm not sure if a used part would ever work, but it has been reported that some modules in these cars that normally need software can been used in another car. Used parts generally can't be programmed to another car. (xemodex does reprogram some)

    Fuse 20a? - Wiring diagram shows fuse 13 in the 15/36 fusebox, and f3 in the CEM being relevant. Hope the diagrams help.

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  5. #5
    Join Date
    Dec 2004
    Posts
    8

    Default

    Quote Originally Posted by hoonk View Post
    If the seat switch/module got wet it could have been damaged. - I've not done a seat module on the 2008+ cars but the earlier ones (2001-07) needed a software download to make them work. The parts catalog shows software being needed when replacing that part on your car. From experience during a seat module replacement, the seat would move with the NEW module, but needed software to make the memory function.

    I'm not sure if a used part would ever work, but it has been reported that some modules in these cars that normally need software can been used in another car. Used parts generally can't be programmed to another car. (xemodex does reprogram some)

    Fuse 20a? - Wiring diagram shows fuse 13 in the 15/36 fusebox, and f3 in the CEM being relevant. Hope the diagrams help.

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    Sir,

    Thank you very much in advance. Just returned from a quick military trip and ready to tackle this now. I see via your diagrams that the PSM labeled #12 SW on your diagram list is what I need to be addressing. Where is it actually located in the car? I see the part ordering number is 30764849 but cannot find a pic of it on the internet for reference. Does it go on the CEM or is it located under the seat? My fuses are all definitely good so I think it is this actual part #12 SW on the diagram listing.

  6. #6
    Join Date
    Dec 2009
    Location
    GA
    Posts
    1,252

    Default

    Quote Originally Posted by brickson View Post
    I see via your diagrams that the PSM labeled #12 SW on your diagram list is what I need to be addressing. Where is it actually located in the car? Does it go on the CEM or is it located under the seat?
    #12 is the part number for the SOFTWARE that tells the NEW #10 power seat module to work. (the software is installed using VIDA with a valid subscription, either by a dealer or a independent shop with that capability)

    The PSM looks to be in the seat switch assembly, earlier cars it was a box mounted to the bottom of the seat and the switch was separate.

    I would not randomly replace parts that you "think" are bad.

    As I mentioned earlier my only experience with seat modules on CAN network cars has been with the 2001-07 years. Those years the seat module was mounted under the seat. You could replace replace it and the seat would move, but a software download was needed to get the memory function to work.

    If you had the stolen copy of VIDA/cloned DICE (sold on the internet), You could probably activate the seat motors to be able to test them. (and move the seat back into a reasonable position)

    If it were me and I did not have access to VIDA and still wanted to possibly throw away some money GUESSING at what the REAL problems is -

    I would source a used seat switch assembly from a junkyard and try it at the junkyard before purchase to see if it works.

    Then a trip to a capable Volvo shop or the dealer might be needed to properly diagnose and repair the problem.

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