Can’t figure out what’s wrong with the car, what could it be?

Hello, if your vehicle shows 9 volts output while running - well, first i'd make sure you have accurate test equipment. Then, i'd have to tell you to check the battery first to ensure state of charge and the ability to sustain a load. If your battery is above 12.5 volts and doesn't drop below 10.5 volts when under load, then we'll call it good. If it drops and continues to drop below 10 volts - then i'd get a known good battery in the car. After this, further testing of the charging system is needed. Your alternator output at 2,000 rpm of engine speed should be above 60 amps -- and the volts should be right around 14 -- both at the same time. If amps are much lower, or volts are below about 13.8 - then the alternator does not pass. The battery light coming on is evidence of a charging system issue. I question the testing performed thus far and suggest what I've indicated above. If you need more help -- https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.