My car will not start unless I jump start it.
I had the battery and the alternator checked and they were fine.
Any idea of what this could be?
Check the battery cables.
These connections can become corroded and stop transmitting electric current.
Also check the alternator belt to see if its worn. If not, then it’s the alternator.
The wiring on it may be wrong, but most likely the alternator gave out. But first check the belt.
Make certain that the charge that is being produced by the alternator is actually being fed into the battery.
Also make certain that all accessories are getting turned off with either the ignition switch or manually.