My test light is very dim, when testing the fuse box AC spot, when the fuse is out. I do have the truck running and AC going full blast.
Jul 13, 2018 at 7:13 AM
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STRAILER
AUTOMOTIVE REPAIR CONTRIBUTOR
54,178 POSTS
This sounds like it can be one of two things, first I would check the alternator output.
If it checks out I would wiggle the positive battery cable (truck running) to see if the voltage comes back if so the positive battery cable needs to be replaced.