My 2000 SSEi has the "Memory Seat and Mirrors" option, with buttons to recall saved seat and mirror position for two drivers. Sometimes this works, sometimes it doesn't. The dealer has looked at it a couple times now and insists that there is nothing wrong with it (of course it works when you get it to the service department).

Has anyone else had problems with this? Any suggestions?

Thanks,
Rich

Are you having trouble with saving positions or recalling positions?
Are you using the correct key fob "1" or "2" to unlock the doors?

No problem with saving positions.
Yes, using the correct key fob.

This problem is not just with the key fob - it also occurs when I push the button in the car for setting 1 or 2. It SEEMS as if this might be related to the battery voltage (just a guess) - for example, if the car has been sitting a while this seems to happen more (hit the button or key fob and the seats do not move, I have also noticed that sometimes the seats start to move but stop before they get in position). After driving a while, it seems to work again (which is why it works after driving it to the dealership).

As far as recalling positions while in the car...I think that might be a safety feature. I.e. you don't want someone to get squished against the steering wheel or pushed back so far that they can't reach the pedals while the car is in gear. If the seat is already in a saved position, pushing either door or key fob button will not change it.

Have you had the dealer check the charging system. The car is going on four years old now.

This feature ONLY works when the car is in PARK. As you indicated, the seat memory feature does not work at all when the car is in gear - this is how it is described in the owner'* manual.

My problem is that sometimes it does not work when it should (when in PARK).

Yes, may need to have the charging system checked.

Not sure if this helps or not, but my folks bought a new 2003 Envoy.... and they had the same problems. They had to get some part (computer?) replaced and then it worked fine. I remember because they had to order this part in and it took a few weeks.

Not sure if the memory systems in a GMC Envoy are similar to a Bonneville or not, but they control the same things... seats/mirrors via the fob.

Put your driver information center display on volts. mine reads 14.7 to 14.9 usually, with rear defrost on and braking it drops to 14.3 to 14.5.
The memory seat module is under the drivers seat and it is connected to several limit switches. If one of these has a poor connection the seat memory system will not move the seat. Maybe the reason it starts working after a while is your weight has shifted the seat and made the poor connection?
You may want to run a calibration of seat movement for the memory module, that may help and its easy to do, from the shop manual:
The memory seat module uses position sensor inputs to establish soft stop locations for the adjuster motors several millimeters ahead of the physical limits of the adjuster assembly. After replacing a memory seat module or adjuster components, it may be necessary to reset the adjuster motor soft stop locations. When the repair procedure has been completed, operate the seat adjuster switch in every direction until the seat adjuster reaches its mechanical hard stop by repeatedly pressing and releasing the switch as necessary.