I explained a bit how 4wd is engaged in these trucks in this thread:
http://www.4x4wire.com/forums/showflat.php?Cat=&Number=935608

I can't see how engine temperature would have any effect unless maybe there was a loose connection somewhere that opened up when heated...?


'97 4Runner, '06 F350, '86 4Runner, '05 WR450
http://home.4x4wire.com/erik