Just got a 2002 Envoy that has been parked for 2 years. The transmission was slipping so I changed the filter and fluid and it doesn’t slip now, but the only way it will change gears is when the revs get up I have to back of the gas then back on the gas to get it through the gears. But it only works in A4WD, won’t go into 2 wheel. The lights flash back and forth for 2hi but it won’t go in, goes back to 4 wheel. Also there are 2 plugs that are unplugged and all corroded under driver’s door on the frame that go into a box with what looks like fuel, brake, or transmission lines. Anyone know what these are for. Could they be connected to the transfer case problem in some way?
