2000 deville suspension

We always need trouble codes ("DTC") to point you in the proper direction. Read post #2 at this location to display your codes http://www.cadillacforums.com/forums/cadillac-tech-tips/55172-how-pull-codes-got-codes-warning.html

You are interested in C prefix codes for this situation. And it sounds like your Electronic Level Control exhaust valve might be causing the problem.

But we need the codes first.

i already checked the codes. there are no current codes, everything is all history

History codes can still lead you to the problem since some do not remain current once the ignition is cycled. Could be that the level sensor switch is not shutting the compressor off, possibly a bad switch or dirty contacts. In that case the compressor could run until it times out. Does the back end cycle up and down or does it always sit ass high?

it's always up high.

Dump the the air pressure by removing the air line attached to either one of the shock bags.

Then let the compressor do its test cycle at KEY ON. If the back end stays up, you will eventually get a code.

Sounds like a bad exhaust solenoid valve. I'd expect one of the following DTC's.

C1737 - Exhaust Solenoid Valve Short to Battery
C1738 - Exhaust Solenoid Valve Short to GND

JimD said:

Dump the the air pressure by removing the air line attached to either one of the shock bags.

Then let the compressor do its test cycle at KEY ON. If the back end stays up, you will eventually get a code.

Click to expand...

i did dump all the air pressure but it went back up. i drove around for about half hour but still no new code beside the ones i just posted. and i got those codes before i dumped all the air

Check the actuator/sensor under the rear end. The linkage arm may be bent, broken, disengaged.

is it under the driver side?

I think it is on the passengers side.

i have an 2003 Base deville with the soft standard suspension its on the left (drivers). Its inside the wheel well just front of the middle of the tire. There should be a sensor with a maybe 6-7" bar connecting the frame mounted sensor to the suspension. There are identical cut outs on the passenger side for another sensor but i believe that's if you have the active suspension. Or possibly the optional stabili-trak.

What would happen if I take out the sensor out of the suspension

The ELC will no longer work.

here's what he's really asking: can the standard height be adjusted to bring the rear end down? Would be nice if the car had a more level stance. The shape is so wedge-y and then the tail is up in the air on all of them
I've ever seen.