2000 blazer turn ignition on and hear click click buttons give a quick flash and that's it. Checked corrosion, checked tightness, checked for shorts. Took it in to have it read and came up a no read. HE looks through the fuses and said the one under hood was blown. Changed it read it again and said it was a no read still. Reset it with scanner and magically had 4x4again, for a half day. If it came up as a no read what did he reset? Checked fuse again and its fine. Same thing turn my key hear clicks coming from tccm quick flash of the buttons and nothing. Wtf I don't think its the tccm because when it clicks and buttons flash that is it running its diagnostic mode. Maybe I'm wrong though.

 

If one of the fuses that powers the TCCM was blown, the codes in the TCCM would be reset. The BCM (body control module) will trigger a 'service 4wd' light if it cannot communicate with the TCCM, but the BCM does not store TCCM codes. If you had scanned the BCM for codes, you may have seen a communication error.

Have you scanned it for codes after it has lit up, then gone dead? Have you tested the wiring between the dash switch, TCCM, and encoder motor (wiring information is in the tech article section)?