They can check it on their bench and it’s probably the most accurate.
But also they have a tester that will test your battery, alternator, then starter. In that order though. If the battery isn’t fully charged it can’t check the alternator. And if the alternator is no good it can’t check the starter.
But it’ll let you know if the whole system is good or not.
The biggest issue is, that with vehicles this old it could be anything from major components, to bad or degraded wiring, loose connections, corroded terminals.
You kind of just have to jump in and start isolating issues. In the military we call it half splitting. Start in the middle and work your way forward, or backwards. If you don’t find the issue, work the other direction.
But also they have a tester that will test your battery, alternator, then starter. In that order though. If the battery isn’t fully charged it can’t check the alternator. And if the alternator is no good it can’t check the starter.
But it’ll let you know if the whole system is good or not.
The biggest issue is, that with vehicles this old it could be anything from major components, to bad or degraded wiring, loose connections, corroded terminals.
You kind of just have to jump in and start isolating issues. In the military we call it half splitting. Start in the middle and work your way forward, or backwards. If you don’t find the issue, work the other direction.