This was the case for mine , might be different for OP. I had to rip out the vanity mirrors completely and tape off the electrical ends.

I new something was fishy when a 6 hour old Duralast Gold Battery was dead.

 

fink99,

Not an easy thing to find. I had to make some new ends for my multimeter so I could connect to the fuse box and close the Blazer 's door. Had a draw of .17 amps after the lights went out, that gave me a idea where to look. Made the wife happyas she uses the Blazer not me.

MG DAVE