Hey so a couple weeks ago i got a new battery because the light came on and it turned out the battery was bad. I made sure to have them test the alternator and everything passed. Then the engine light came on, turns out I needed a new EGR valve. no problem, got a new one and replaced it but now my battery light keeps coming on then turning off. Can't figure out why, nothing looks like it was knocked loose.

 

Use a voltmeter to check battery voltage with engine running to determine if the voltage goes up and down with flashing light.

may have alternator or wiring issues connection issues. The wiring/cables could look OK but have a loose connection. Check alternator brushes.

Could have someone watch the light as you test wiring connections at alternator and battery.

Don't run the engine with battery cable disconnected or the alternator will be damaged.