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On the first replaced alternator (which turned out to be bad), it only happened once, and the battery was dead and were not able to start back up -- this alternator tested bad so it was replaced a second time.
During a test drive today after mechanic checked battery, alternator, and all circuits and wiring for amperage and all were good, and OBD showed no fault codes, he said it died on him. Initial attempts to start failed, so he waited 5 minutes, and then it cranked right up, and the battery was not drained, which makes sense since the second alternator is still testing good.
Said he looked for "freeze frame" codes on the OBD afterward and nothing showed. His theory is that some component is randomly sending a code to the PCM which shuts it down.
As to per day, since the alternator was replaced a second time approx 2 weeks ago, only happened once to my son on Tuesday, after which I recharged the battery to make sure I could drive it to mechanic, and checked for amp draw with ignition off to see it something was drawing current overnight (no draw). The next time was what I described above, to the mechanic on test drive after they could not find anything testing bad. Said something like "we're at the point where we would have to start pulling panels off and charging you" since all fuse box and wiring tests came up with nothing.
Ok.. so when the engine stalled and did not start up, was the engine able to crank over and not start or was it not even able to crank over at all?
Time 1 when my son was driving, it wouldn't crank at all. He called police since I was asleep. They tried to jump it to no effect, so he had it towed home to me (because my sons believe Dad can fix anything, which is almost true...this son has Schizophrenia, under control by meds, but he is now afraid to use the car unless and until we isolate the issue and fix it, which I totally understand!).
Based on my memory of what the service advisor said when it died today, it didn't crank at all for him either, yet a wait of 5 minutes and it was good to crank and go.
Ok.... if the engine did not crank over when this happens, you either have a bad battery, bad connection at the battery, a bad connection at the fuse block or fuse box under the hood or maybe a bad ignition switch.
Next time this happens, you can start by checking battery voltage. If the battery voltage is 12 volts, then move to the fuses under the hood and check to be sure that they all have the same power as the battery. If they do not, then you have a bad connection from the battery to the fuses. If they do, then go to the fuses inside the vehicle and make sure that they all have power to them with the key on.