4 Wheel Drive/SUVs: service 4 wheel drive light, gm product, gears

Question
my service 4 wheel drive light will come on after the vehicle has ran for about 15 min. and also it will either start out in auto 4 wheel or 2 high. i cannot get it to shift into the 4 high and 4 low. the light will blink on and off in the 4 high and low but does not switch over. this has went on for some time now. what do u suggest i should have looked at for this problem. i really need my 4 wheel repaired before winter. help.   :>) Jodi

Answer
Jodi, I am assuming that you have a Gm product, it might be the transfercase motor , or it could be possible that the forks inside your transfercase are wore enough that they are putting the gears on a bind . That seems to be the problem with alot of Gm transfer cases . ADAM