1999 Ford Expedition CODE P1633

Yes, I did have the actual battery replaced and the terminals cleaned. My major problem is that you stated the engine light should be on, but my engine light service only comes on periodically such as when the car is overheating, needs oil or antifreeze collant. Other than any one of these conditions, my service enging light does not come on and it does not remain on all the time. One repair shop told me he would have to trace the entire wiring system from the battery all the way to the starter to diagnose the problem. I believe this is extensive since the car is running good except jerking from the rear, but other than that is runs perfect w/o any hesitation and stalling at all. Please help me if anything changes. PS---how bout the MAF-mass air flow I heard it causes this problem, is that correct because many of them goes bad on this and many other ford vehicles.
Thanking you in advance.
Evette

That is what I was told by one mechanic, but my engine light only comes on periodically, and not that often at all. I only seen it about three or four times since May, 2009 when I first took the emiissions test. However, the auto zone store has since reset the code p1633 and the care was checked out by anothet mechanic who said even though the code was reset it still remains there on the scanner, although is was reset. It was read not ready when the emissions was just checked prior to a reset. My problem is that the mechanic that checked it on his scanner said the codes definately indicates an electrical problem from the battery terminals to the computer and he wants to replace the entire harness and maybe even the computer. There was also an heated sensor circuit showing on his scanner when he checked it. This guy wants to charge me a whopping $350 just for the replacement of the harness and additional cost for the heated oxygen sensor and only god knows what for the computer if need be! Unforunately, I just can't afford this astronomical fees and my check enginge light is not even on for the most part. Dont know what else to do with this problem because the truck, unlike most expeditions runs perfectly. I just drove it from Philadelphia to Georgia and then back and force to Fl a few times without any mechanical problems. I badly need to know what to do. Thanking you in advance.
Evette

OH! I forgot the code p1000 also showed on the mechanics scanner. Does this mean maybe I have to complete a drive cycle in order to get a proper reading for the actual test since the code p1633 was reset? Sorry I forgot about this code in the previous reply to you.
Thanks, Evette