so i just got this 2000 blazer about two months ago, ive used 4 wheel drive about 4 times and everything worked fine. last week i realized it had trouble engaging at first but finally did. my service 4 wheel drive light came on for two minutes then went off and remained off. now when i try 4 wheel drive it just keeps blinking. i can hear the clicking from the module and just replaced one of the vac hoses but no luck. please give any tips, thankyou