Front suspension goes down and does not come up mostly at night. Sometimes as i start the car in the morning it comes back up and stays like that all day. but not always

is this car the all alluminium xk model ? if so it sounds like a bad earth the earth studs are all bonded to the body and are prone to detatching from the body and causing all strange probs. the favorite ones are both front behind the wheel arch liners, if its the older xk still sounds like a bad earth poss behind the headlamps. the only other probs i had was wires coming detatched/poor connection from the column switch, hope this helps

check for4 a faulty air pressure regulator in the system or faulty pressure relief valve.

most likely you will find that there is a plastic gard up above the tyre. if it has come lose then sometimes one end of it can flop down and rub aainst the tyre. this will usually happen when you go through a dip because the suspension let the tyre go closer to the gard at the same time the plastic bit hangs lower as the car goes through the dip. when my car did this I also found that when I tok my foot off the accelerator the front of the car would drop down causing the suspension to do the same thing as when it goes through a dip. also some corners and and uneven roads do the same thing.

check your air lines where they go into the height sensors in the front-you don't say if it is just the front or back, or the entire system, but if it is the entire system, look at the lines that go into the dryer and make sure they are pushed in all the way.

it should deflates only at trim height and shld stay at that level considering that there is no leak on the rear air suspension. Most probably leaking rear air suspension is the problem. The system works up to 45 minutes only after ignition off and will maintain the trim height

I have owned several air suspension vehicles. My Expedition was similar to yours. You may want to try the 4x4 switch because it will raise the body 1-2 inches higher. Checking its fuse would not hurt.

On most of my vehicles the suspension would work end to end, raising the front first. You could have 2 issues with the suspension. There should be valving to switch the air to the rear suspension after the front is up. I would wait longer for the rear to catch up.

If I had to guess why the front lifts first it would be to get the front off of the curbs and sidewalks when you park so the bottom doesn't drag.

There is a diagnostic plug for the air suspension and sometimes Autozone or Oreillys have the scanner for that special plug. If not, some alignment shops and all dealers would have it. Also Ford parts are often the same as Lincoln and cheaper., Someone may make aftermarket parts at a better price.

Check to see if the plugs on the wheels are plugged in check that the pins are all the way into socket, that your ABS problem, next check to see if you knocked loose the wire on the differential most likely cause and be sure to top off power steering fluid. Check that the fluid level is ok on the Diff. if you need more help let me know and thanks for using Fix-ya and rate if this was helpful.
Avid101

The air suspension uses the same vent solenoid to vent front so that will be ok. The problem will either be the rear height sensor which mounts on/near left side of rear axle. Or the air suspension module itself.
I would suspect it is the rear height sensor,the link may have come unhooked or it may be sticking or just bad.

leaks can be difficult to find in these systems. They could be in the air springs themselves, the air lines etc... not to mention you could have a ride height sensor that is malfunctioning or the control module. A lot of people are converting these old cars from the air ride suspension system to a standard passive coil spring conversion. A high quality, powder coated, American steel coil spring is DESIGNED to last the LIFETIME of the vehicle. http://www.strutmasters.com offers conversion kits with a lifetime warranty so youwon't have to worry about your suspension again. Give them a shot.. it definately beats the dealer price of around $1200 to fix your air ride.

level change up to 20mm in 24 hours is normal.
if after start car returns to normal level you do not have problem yet.