Electronic Level Control

I have a '97 Lesabre Limited with Electronic Level Control. The rear of the car was sagging so I started checking it out. I found the compressor all rusted up so I replaced it. The new one is not running either. Can someone tell me how this system works? I understand that the control arm/rheostat sends a signal to the computer which turns the compressor on. How can I test this system?? I have a good digital volt/ohm meter but the repair manual I have doesn't show any wiring diagrams or other info for the ELC.<P>

<P> The most common failure point is the $300.00 sensor on the rear suspension. The system can be functionally checked by disconnecting the little arm from the rear suspension mount and moving it up and down to see if there is any reaction from the ELC system. Beyond that, you really need connection diagrams for troubleshooting. The GM FSM has these in it.