So I thought I had it all figured out, thinkin' I was fixing Code 1790 (RR air spring output circuit failure) with the replacement of the air spring solenoid pigtail connector (https://www.ford-trucks.com/forums/9...t-circuit.html)). The code came back again so this time I checked the component side (solenoid) more carefully and found there was an open circuit in the coil - the way I tested it was taking the old connector and stripping back about 1/4 " of insulation on each of the wires (black wire (which is ckt 57/ground) and pink/black wire (which is 114 to power/signal from suspension control module) and removed the locking clips to make it easy to slip on and off the solenoid for testing. Then I pulled the existing, recently installed pigtail off of the solenoid and slipped on the 'test pigtail' with bare wires hanging down. Tried to get a resistance reading on the solenoid but got nothing; then tried a simple continuity test and bingo, no signal or sound. Turns out the solenoid was indeed faulty as well as the old pigtail! Luckily, I had purchased a spare rebuilt solenoid from Americanairsuspension.com and used that as the replacement.

So here's the problem, or my question to you all: I had been hesitating to replace the solenoid because it appeared to me that the air spring was indeed inflating somehow. My question is - Does the solenoid of the working air spring also inflate the other air spring with the broken solenoid because they share the same rear air fill line? The only way I can see that working is if the broken solenoid failed in the open position allowing air to enter. Does this make sense? Does anybody know if these solenoids contain some type of spring/check valve inside? Either way, the new replaced air spring solenoid fired up quickly and for the first time in years, it appears that the vehicle does not have a slight lean to the drivers side. Weird, but I guess it was the solenoid all along, possibly I was driving it like that for years (?). Another lesson learned about LLS....

 

If the solenoid was stuck in the open position it would air that spring whenever the compressor comes on to air any other air spring, at least thats the way it was on my Mark VIII. Each solenoid adjusts the suspension according to it's needs by opening, no compressor on when lowering and if only one spring demands air the whole system is pressurized to the solenoids with the only one being serviced is the one that the computor tells to open. I hope that was clear as it was a lot of words to say yes.

 

Thanks, Mel. Yes, it was clear. Your description also follows some of the other Lincoln sites I've been following where articles there describe the same behavior of the system. I guess with all your knowledge and that of those of us who have been fixing/learning/tinkering our LLS components/systems and sharing it on this site and others, we could all write a book on LLS! We test drove it yesterday after the repair and the suspension feels like the day we got it. I'm putting in new shocks on the rear, Bilstiens, next. Thanks for the help.