4x6 in the front dash
Begin by removing the dashboard speaker covers on your 1989 Chevy S 10 Blazer. Remove the speaker retaining screws. Remove the speaker wiring harness. The speakers will come out.
The 93 K1500 Blazer has 4 x 6 inch in the dash, and 4 x 10 inch in the rear.
It looks like color coded spaghetti.
There is a very good description if you click on the link on the right.
Check the left side of the dash with the drivers door open. the door hides the access to the cover for the fuse box
under the dash
The alternator is failing.
Analog dash IA a 1991 chevy s-10 blazer
Behind the passenger side of the dash.
Be sure the dash illumination dimmer switch is not turned off.
Under the left side of dash.
Under dash, drivers side.