AWD Delay

[NoName]

This started a couple months ago before i did not have this issue. When i am in the snow, my front wheels will spin then anywhere from 1 - 5 seconds later my back wheels will kick in. If i am giving it lots gas it will make a big clunking sound when the back wheels kick in. I had the car in a transmission shop for some work(replacing torque converter) I mentioned the awd delay issue to them. They said they looked it over and said that it had to be an electrical problem that everything checked out ok when it was apart. What electrical stuff should i look for and how should I test. Or what other things can i check to try to clear up this issue.
Any suggestions would be great.
I searched the forums to look for some info but didn't find any clear answers or ways i can check electircal components.