i have a 1998 ford EB Expedition. rear end sagging after 2minutes and 25 secs the check suspension light comes on. i have a C1770 code and a C1756 code. i was advised to replace the WAS control module above the radio. most ford people say this module seldom goes bad.

how do i diagnose what to repair. i have new compressor, new rear bags with life time warranty and i have replace the relay behind the headlight fuses are good. the vehicle will not lift with the key on and hard wiring the compressor to run.

please help pkaelin