My Four Wheel Drive Does Not Work
You tried out your four wheel drive and found out it does not work. This dilemma is common and is related to a couple of the 4WD systems. If you own a 1980 or 1981 Eagle without Select Shift then you have a bad transfer case -- these cars were full time 4WD and seldom had any 4WD issues.
For the rest of us with either version of the select shift cars the most likely problem are that somewhere in the vacuum distribution system there is a leak caused by bad lines or lines which have become disconnected. The repair is easy, though patience is required. Basically you need to renew all the lines and make sure everything is connected properly.
If you have renewed all of your lines but it still does not shift properly then you probably have a bad vacuum shift motor(s). All Select Shift Eagles have one on the Transfer Case and Select Shift cars from 1981 - 1984 also have one for the front axle disconnect. You will need to determine which one is bad and then determine how you want to repair it. Either with a new shift motor or thru a manual shift system.
Front Axle Lock (1981 - 1984 with Select Shift)