When I attended factory electrical training in Detroit with Cadillac back in the early 80's our instructors ALWAYS taught us to check your GROUNDS, CONNECTIONS and FUSES before you did any other diagnostics. If you didn't the punishment was intense!
"Pay attention to the details! It ALWAYS pays off."
1949 Chevrolet 3100 Series 1/2 ton Pickup 1964 Chevrolet C10 (Ol' Yella) (SOLD) 1958 Chevrolet Biscayne 2 door (SOLD) 1970 VW Beetle