It used to work flawlessly for two years. Now the winter is coming, and I wanted to test out shift-on-fly 4wd on my Trooper 98. The problem is that most of the time it will take 2-3 minutes to engage, green light keeps blinking all the time. Sometimes it kicks in within 5 secs, just like it used to do all last winter. Mechanic checked the darn thing and can't find anything wrong, it seems to engage just fine when in garage, and vacuum sucks as it should.
Any ideas what could be wrong? I'd rather fix it before snow comes.
Peter