I have a 2004 Blazer that has issues with 4HI. I have researched this but still not sure what to try to fix it. Here is what is going on. Perhaps the history of it can shed some clues. The 4hi started acting up winter before last. I would hit the switch (3 switch controller on this truck) and lights would go bezerk. 4Hi would not engage. However 4 Lo works perfectly. I found that if I unhooked the battery for 8-10 minutes the 4hi would work again. I could get 3, 4 uses out of it before it would refuse to work. As I don't use it a lot I got by with this for a while. But last winter I did this and while the light did show 4hi, it never kicked in and I had to switch to 4lo to get up a hill. So far I have inspected the TCCM for dirty connections, looked at the actuator(it looks great but have not tested it yet). I know this vehicle was rarely used in 4wd by previous owner, if ever. One garage thinks it is the motor but since the 4lo works well and has been used little I am not so sure. I know a lot can cause issues with these. Do my problems shed any clues??