My 4wheeldrive all lights come on and loose power 1999 blazer any ideas?

Hello, if the 4 wheel drive light illuminates accompanied by the rumbling, it could be an issue with electronic controls of your transfer case. Alternatively, it could be an anti-lock brake system or traction control problem. In either case, diagnostic testing utilizing a proper diagnostic tool to retrieve diagnostic trouble codes (DTC's) needs to be performed. When a warning light illuminates, it's an indication of a code being present -- and these codes are quite helpful in drilling down to the root cause of your problem.

This should help: https://www.youtube.com/watch?v=BeBwrjFYq7M You're hearing the front axle trying to engage although 4x4 isn't selected.