The K-D test light is only 2 dollars. Years ago K-D supplied General Motors Dealerships with K-D tools. Made in USA.
It lights up fine, no issues.
Test power and ground in wiring, switches, and components.
Get into tight quarters or around obstructions with my chrome plated 9/16" Swivel Socket, six point, 3/8" drive, brand is Craftsman.
3 dollars.