2001 Lumbar Inflating by Itself

We've had our 2001 Tahoe LT for about 6 months. It's got the plush leather, power, heated seats with the 2-way memory settings. In the last couple months (maybe longer), we've noticed that the lumbar support in the driver seat seems to automatically inflate all by itself while the vehicle is parked. You can't see it happening, but when you get back in after it's been sitting a few hours, you can tell that it's larger than it was when you got out. If it sits all day, the effect is really noticeable. When you're driving all day and making frequent stops (as we've done a couple times this summer on long road trips), the lumbar seems to stay where it belongs -- or maybe I'm so tired of driving that I just don't notice it.

Any idea what could be causing this?

I don't know how the lumbar support works on this seat. Does the electric pump inflate the seat directly when you push the button, or is there an air storage tank somewhere? If the latter, could this be a valve between the tank and the lumbar that's leaking air to the lumbar?

Maybe I need to pick up a manual for this truck. Would a cheap Haynes or Chiltons describe the lumbar system, or would I need a factory service manual for that?

I have the same problem. It likes to pump itself up. I constantly have to keep deflating it. I have also noticed that it only functions one of the ways. Its Two way adjustable but one of my pumps must be broken because it doesnt inflate the other air bag. I'm just curious as to how many other people experience this.

Well, at least I'm not alone. What year is yours?

On my 2001, the second switch is for the side bolsters. I only have one lumbar bag. I haven't noticed any problems with the side bolsters; just the lumbar.

I have a 2001 as well, LT. Actually, it is my side bolster that keep inflating. Its the lower lumbar bag that wont inflate. my switch is a 4 way switch, up/down, and then left/right for the other.