Hello, i'm a new member and i am having problem in that my 1999 silverado 1500 with push button 4wd shift will work fine when cold but will quit when hot. The light will show that it shifted but the front axle is not engaged. I changed the transfer case fluid and what came out looked like burnt atf fluid. I replaced it with ac delco blue fluid. I haven't seen any info about temperature affecting 4wd shifting.Thanks in advance for any help on this problem.