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06 S80 seat memory behaving oddly

Help, Advice, Owners' Discussion and DIY Tutorials on the Volvo S80 model. Sometimes called an "executive car", the S80 was and continues to be Volvo's top-of-the-line passenger car.
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Volvo Repair Database 06 S80 seat memory behaving oddly

Post by 850TurboTurtle » Thu Aug 10, 2017 7:11 pm

Anyone with seat memory skills? When I purchased my 06 S80 a few months ago memory 1 was the only one working. Then that stopped and it switched to mem 2 works for seats and mirrors, and 3 works for seat only. The key fob memory (where it resets to whichever key fob is used to unlock the car) is also erratic.

So - any ideas what might cause this and a possible solution?



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Re: 06 S80 seat memory behaving oddly

Post by jimmy57 » Thu Aug 10, 2017 9:43 pm

Just to assure you are giving the memory system a chance: On that car the memory system requires that the car be locked and unlocked to trigger the memory acquisition and motion. The car only knows which remote because you open the locked car. Once driven and adjustments are made then locking the car with the remote and the computers shutting down sets the positions to storage. Now if the seat and mirrors are adjusted with another remote used to enter car then when your remote is used to enter it will know to go to your remote's set positions. Avery common issue with the system is that a car is parked in garage at home and not locked as garage door is closed after you drive in. The store and car entry remote acknowledgement doesn't happen when no locking and then unlocking occurs. Another issue arises if only one remote is used in that the car may leave home garage driven with one key by a second person. They lock car at some location and then unlock and drive to another location and lock again. Now their positions they adjusted when they drove car are set. You get in car at home and have to move seat and mirrors.
Sounds like bad system. In Europe home garages are rare and people lock cars when parked on street or in an apartment parking garage so making a system that triggers on locking and unlocking seems right.

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Re: 06 S80 seat memory behaving oddly

Post by Roger_850T » Sun Aug 27, 2017 8:42 am

Per jimmy57's comments, my wife and I mess each other up all the time because we don't lock the car in the garage. You'd think there would be a better way.

Anyway, while I can't tell you exactly what's wrong, I went through a similar diagnostic on my XC90 recently, and can give you a little more info that may help you track this down.

Pertinent electronics are:
- The switch module on the seat (that actually has the buttons)
- The Power Seat Module (PSM), located under the seat - is the computer that controls all the seat functions; is where the seat memory locations are actually stored
- Upper Electronics Module (UEM) - receives the signal from the remotes, stores which seat and mirror positions are associated with which remote. (The UEM can have up to 6 remotes programmed - remote 1, 2, and 3 can store positions, remote 4, 5, and 6 cannot.)
- Drivers Door Module / Passenger Door Module (DDM/PDM) - has the electronics to move / reposition the mirrors

Per VIDA, talking about the UEM:
"If the vehicle has seats and door mirrors with memory, these functions are affected by the remote controls stored in positions 1, 2, and 3. When the car is unlocked using one of these remote controls and the driver's door is opened the information about which remote unlocked the car is stored. The setting for the drivers seat and the door mirrors is stored in that remote control at the same time that the car is put into "sleep mode". (Sleep mode means that the car continues in stand-by mode with low energy consumption, which occurs when the the ignition key is removed and no function is activated for approximately 5 minutes). The next time that the car is unlocked using that particular remote control the driving seat and the door mirror positions will be set to the same positions that they were when the car stored the information."

Thus, when you unlock with the remote, the UEM sends a CANbus message to the PSM to move the seat, and the DDM and PDM to adjust the mirrors. IF a memory location has been set. If not set, then it doesn't have anything to send.

In my XC90, the mirrors only reposition with the seat memory if the car is on. If my wife has bee driving, car is in the garage, unlocked; I open the door and press "Memory 3" to move the seat to my position - only the seat moves. Once I start the car, I press "Memory 3" again and the mirrors reposition. I suspect that if I got in the car first, started it, and THEN pressed the "Memory 3" button, both the seat and the mirrors would move together.

So, with all that in mind, and knowing what has to communicate with what else, it might be easier to troubleshoot your issue.
- Is it the button on the seat panel that is intermittent, or will the button always take it to the stored location? (The switches inside the button panels can wear.) If the buttons won't program, then look no farther than the switch panel (probably) and the Power Seat Module.
- Is it a "remote coordination" issue where different remotes get used and it doesn't properly save the positions
- In general I would not expect communications between the modules to be intermittent for this. (If there were a CAN Bus issue, you'd have a lot of other problems too.)

I hope this helps!


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