03 Expedition Transfer Case Woes

[Drae]

Recently the front driveshaft u joint broke off the transfer case end while my wife was driving. After replacing the front driveshaft, replacing damaged shifter cable, mlps, gear shift lever and tranfer case vent valveback in my truck it was stuck in 4WD LOW. I put it in 4WD LOW while taking the driveshaft bolts off and reinstalling them so the transfer case wouldn't spin. Well when I went to drive it I put it in 4WD HI but the light was still showing 4WD LOW. I drove it and could tell it was still in 4WD LOW as I could hear a gear whine and it seems as it wasn't shifting past 2nd with high rpms. So I went back home and did some reverse driving and foward while putting the truck in Neutral and park while switching between all transfer case gears and it finally went into 4WD Hi and was functioning properly into all selections. It drives well while I'm driving but twice within a week while my wife drives it, it acts as if it's in 4WD LOW when the light still reads 4WD HI. Just wondering if this is common and possibly a fix without swapping out the transfer case. Getting her to explain exact details before it happens is like pulling teeth. Maybe a solenoid issue or transfer case motor malfunction? I'm up to any suggestions.

 

[Drae]

Well I just found out the input seal where the transfer case meets the transmission is leaking letting extra fluid into the transfer case from the transmission output shaft. I took the fill plug out and it just spewed out all over the floor. Thats why my transmission fluid was a little low about a month ago and had to add some. I will be getting a used transfer case and have a new seal put on it and swapped out. I will rebuild the one in the truck to have as a backup. Would this cause the transfer case to suddenly go into 4WD LOW at times?