My 2003 Olds Shilouette air shocks work but the sensor for the load must be out. With a load the air compressor is not signaled to pump. The pump works when I activate the auxillary button. Where is that sensor and how can I know if that is the problem.

My 05 lesaber compressor quit working and what caused it to quit was the old air struts wore out and made the compressor run all the time causing it to over heat and burn out. Rather than replacing the air shocks and compressor my mechanic installed a set of air shocks and installed an air line from them to a spot below the trunk lid on the bottom of the trunk. They have what looks like the air nozzle for a spare tire I use an air compressor or even the air pump you blow up a spare tire. I keep about 60 pounds in them all the time and check the air pressure abour every three months. Cheaper doing it that way.

Ford Air Ride Rear Suspension Down Diagnosis & Fix ...

? 9:57
https://www.youtube.com/watch?v=wfh7n17hvN8
Feb 24, 2014 - Uploaded by FordTechMakuloco
Ford Air Ride Rear Suspension Down Diagnosis & Fix ... why theair ride compressor is not turning on and pumping up the air ridesuspension on your truck. ... Ford Expedition & Lincoln Navigator Air Ride C1725 Common Faults ... 2000 Ford Expedition - Replacing the rear shocks with load leveling shocks ...

2003 Lincoln Navigator air suspension fix(3) - YouTube

? 3:41
https://www.youtube.com/watch?v=MhWlcYycny4

Plug in those shocks. Sounds like your hearin the fuel pump cause its the only thing that would make noise with engine off. U need ur compressor just leave it be.

Would need to know what DTC'S - diagnostic trouble codes are stored in the module for the autoride suspension . Hooking up a professional type scan tool ,looking at input data to the module etc... Looking at a wiring diagram an testing electrical circuit's using a DMM - digital multi-meter . Reading how the system works ,what all involved in making the system work . This is how a professional Tech would go about diagnosing this .

The automatic level control (ALC) system maintains a desired rear suspension position under all types of towing, hauling and loading conditions. The following components are involved in the operation of the ALC system:
• Air line tubing--Pressurized air from the ALC compressor is pumped to each of the rear shocks via air line tubing.
• Air drier--Pressurized air from the compressor is run through a drier containing a moisture absorbing chemical preventing water accumulation in the rear shocks.
• Compressor--Supplies pressurized air to the rear shocks
• Compressor motor relay--The relay supplies battery positive voltage to the ALC compressor motor.
• Pressure sensor--The electronic suspension control module (ESCM) module provides a 5-volt reference and low reference to the ALC pressure sensor. The module receives the signal voltage that is relative to the air pressure applied to the rear shocks.
• ESCM--Controls the ALC system and electronic suspension control (ESC) system and detects failures in both. The module monitors inputs from the position sensors, and pressure sensor to determine when to raise and lower the vehicle to trim height as the vehicle is loaded or unloaded. The module limits pump activation to 255 seconds to prevent thermal damage.
• Exhaust valve--An electric solenoid activated by the ESCM to vent air pressure from the rear shocks.
• Left and right rear suspension position sensors--The module provides a 5-volt reference and low reference to all 4 of the body-to-wheel suspension position sensors. The sensors send the ESCM a signal voltage that is relative to the rear suspension ride height
• Left and right rear shock absorbers with internal air chambers and dampers--Dampens the rear suspension and maintains trim height depending on the air pressure applied.

No, but you can put the 50-80$ sensor in too correct the system considering you just spent 500-600$ to have the pump replaced. Or you can just put non-air rear shocks on the vehicle although the suspension system will generate a warning message on the dash.

Check the electrics and sensors to the pump

The load leveling shock will not work if there is an issue with the compressor. If you buy the sir shock's, your going to have to address the compressor issue to even have the air shocks level the Silhouette. Once you have the compressor issue addressed, the shocks it's self is simple enough to replace that you can do it with common tools to save you some money. My wife has a Montana and we had the same problem, since we do not tow and really never hold that much weight. We replaced the rear shocks with Monroe Reflex Shocks, Found the van to be much more sturdy then the air shocks ever were and the good thing about them is there were lift time replacement at Parts Source. Regardless on which shocks your going to use, it's a good rule to replace both sides at the same time. The only difference in to reinstalling the air shocks is you need to reattach the air lines to the shocks and that's simple as removing the shocks it self. The shocks are only held on by two bolts,  one on top and one on bottom and should only take about 20 min each side to do since you have to jack the car up and remove the wheel for room, but you can remove the shocks it self without removing the wheel, it's your preference. Good luck and keep me posted, be glad to answer any questions you may have. 

CAM SENSOR IS LOCATED ON THE TOP OF THE BLOCK ON THE PASSENGER SIDE OF THE ENGINE... UPPER INTAKE MANIFOLD MUST BE REMOVED TO GAIN ACCESS ..

That is an indication that your air shocks at the rear needs to be replaced or there is a sensor that may have gone bad, event the air pump mey not be working. Most owners replace the more expensive air shocks with good conventional shocks like Monroe Reflex Shocks if there not towing heavy trailers. You can have the conventional shocks installed and have the ride control system deactivated. First check your fuse just t make sure the fuse to the air compressor has not gone bad, and the air ride leveling sensor, wire harness has not been damaged due to corrosion. 

Check the height sensor.