This problem occured 2 days and 2000 miles after I had a reman transmission unit put in car. My scanner worked at that time and I got a Lock Circuit Voltage low code and a lost communications with TCCM code right after. Ever since then the service 4wd light has been on and the switch for engaging the system doesnt function anymore. To get it to work I have to reconnect the battery cables and pop in a new fuse. After that it works long enough to get me out of a crappy a situation but it burns after. I have been told the motor for the T case needs replacing but it doesnt make sense because it actually works when the fuse is not toast. Maybe some wiring issues instead? I would assume things got moved around down there when they had to replace the tranny.

Any clues would be appreciated.

Edit: 2001 4wd 4 door blazer. 173k miles(mostly highway)

 

In general, fuses are burnt in two cases:
- a grounded power line
- short circuit somewhere on the actuator (more likely would blow a fuse on change over from 2HI/4HI/4Lo etc.)
Did You notice when exactly the fuse blows? I.e. only while push-buttons operations or not? Both grounding or short circuit may not be permanent.

 

I don't think the fuse blowing was related to switching from different settings. Also if you just change the fuse without disconnecting the battery first it will blow before you even get into the cabin...

 

Suggest checking the wiring harnesses for damage from the trans swap.

 

Yup. And I'd go back to the shop, at least get them to put it on the lift.