My 91 Subaru Legacy won’t start, but it will take a jump. When I drove it after the jump the lights dimmed and the radio shut off. It’s turning over fine, and I got the alternator and battery checked out and they are both good. Any ideas?
Have the battery and battery terminals replaced. That should solve your problem.
If you are sure about the battery and the terminals, check the starter connection (+) and (-). It just takes one corroded or loose connection anywhere in the start system to cause the problem you describe.
Have someone else check them out and also check the battery cables. My guess is the battery first alternator second. Cables may well have caused the problem. Connections at both ends need to be checked (removed, inspected and cleaned.) I would also suggest that someone twist and pull on the battery cables when they are being inspected to make sure there is not an internal flat.
Good Luck.