99 Expedition Air Suspension Problem
I am having a problem with the air suspension on my 99 Expedition. I bought the truck used a year ago. A friend of mine told me about this forum. Not sure if I should post this to this group or the Expedition board. Here is my problem:
The air suspension does not seem to be working. When I first start the truck, the "Check Suspension" light is *not* lit. After about 5 minutes or so, the light will illuminate.
During this time I do not hear the compressor kick on at all. In the past I could hear the compressor kick on and run, so I know what it "sounds" like. Now, though, I cannot hear the compressor running.
I took the truck to my local Ford dealer in Madison. They charged me a $75 diagnostic fee and told me that I needed a new compressor. They wanted $625 with labor to replace it. Since I'm not totally clueless when it comes to vehicles (and my friend is a big Ford guy who knows how to do all this stuff) I said I would take a pass, figuring I could get a decent aftermarket compressor myself and my friend will help me install it for a case of Sam Adams.
Now, this is where it gets funky. I ordered an aftermarket compressor on Ebay for $200. I go over to my buddy's house, and in 3/4ths of an hour we have the old compressor out and the new one in. Great! I've saved $400!
But wait... I start up the car... and... The compressor doesn't kick in. Same symptom as before (no Check Suspension Light upon vehicle startup, illumunates about 5 minutes after the car is started).
Hmmm... We take the old compressor, and apply 12vdc to it. The compressor chugs right along. We pull the new compressor out, apply 12vdc to it. Likewise, it chugs right along. Put the old compressor back in, apply 12vdc to it manually, and it pumps up the air shocks, no problem at all.
Ok, now what? My buddy pulls down some info off the web (alldata?), and we see there is a relay that controls the air pump. I don't know anyone else with the air suspension that I can swap the relay with, but it seems reasonable that the relay is toast. So I go back to the dealer and buy a relay. OUCH! $120! For a damn relay! But hey, I figure I'm still $300 ahead of the game from what the dealer wanted to replace the "defective" compressor which clearly wasn't defective.
I swap the relay on the truck, and it has no effect. Of course, the dealer won't do a refund since it is an "electrical" part and there are no returns/refunds on electrical components. What's the likelihood that I have a defective relay from the dealer? Very small, so I doubt that is it.
We did all of this work yesterday. I'm out of ideas now. We were able to manually pump up the air shocks by applying 12vdc to the compressor when the truck was running, so for the time being everything is pumped up and driveable.
But... What else could be causing the air suspension not to work? I'm baffled. Its not the ride height sensors, those clearly work since they pumped up when we "turned on" the compressor manually. It wasn't the relay. It isn't the compressor.
All that is left seems to be the Air Suspension computer, and I can just *imagine* what that costs.
All the wiring looks like it is in good condition. Is there a way to troubleshoot the wiring to see if I'm getting 12vdc to turn on when it is supposed to?
Does anyone have any ideas? I'm really hesitant to go back to the dealer, since they told me the wrong thing to start with.