I know this is a re visit to a much dicussed topic (sorry), I just bought a 1998 EB Expedition, stole it actually but thats a long story, anyway the LLS suspension does its thing, compressor works, cycles as more people get in the rig, but the drivers side is a lot lower than the passenger side. Passenger side looks like a 4x4, drivers side looks like a 4x2, the drivers side air bag does have air in it, and does not appear to leak out, it stays firm, just not enough air, I have not inspected loactions of anything under there yet, so if everyone says its the sensor, where the heck is it? Other than that, I have to say these are nice trucks, I own several Fords and I am in love with the Expedition, I can't beleive I haven't bought one until now.

 

Is it a 4wd or a 2wd?

If its 4wd, then someone else will have to help you with front sensors.

As far as rear sensor, there is one sensor mounted on the rear traction bar. You can get under the truck and access it. Its help on by one bolt (10mm I think??), just loosen it then you can slide it up and down. Up gives more height, down less. There is only one sensor, so it really can not control ride height from side to side in the rear, so I doubt this would be the problem. (If you do mess with this, one note; the movement of the sensor up and down is NOT proportional to the actual rise or fall of the rear end. If you move the sensor up 1/4" you will get more than a 1/4" rise in the rear. On my truck, I raised it 1/8" and got about a 5/8" rise in the rear. Just FYI)

I would look into shocks as the possible problem. You could have one bad shock, thus causing the truck to sit slightly lower on one side (not more than an 1" I would think). Also, some of these trucks have been known to sit slightly lower on one side. You might also want to check out swaybars and make sure they are connected to all the right places. In general, look at your suspension components to make sure everything is connected.

If it is a 4wd, they do have a sensor on each side in the front. Not sure, but it would seem possible that if one side was set lower, then you might get the whole side lower. Others are have more knowledge of this than I do, so I will stop here and let them respond.

Also, If you do mess with the system, turn it off first before doing so. The switch is located under the dash near the passenger kick panel.

 

Yes it is a 4 wheel drive, I guess I left that out, thanks for the reply, the front sits level its the rear end that sits low on the drivers side.

 

I have the same problem on mine. Ocassionally, though not always the drivers side will sit low when parked. I suppose it's that way when I'm driving too, though being inside the vehicle it's hard to tell. Every once in a while, before I head out of the driveway, I'll throw it in 4Lo and let the bags pump up all the way and then put it back in AWD. This seems to help with it for some reason. I guess it allows both rear bags to fill up all the way and levels it out.