My 2002 Toyota Celica gt. (Automatic) recently started flashing the battery sensor. Over the weekend I drove the car on the highway fine then all of a sudden the car completely shuts off and had to be towed. I purchased a new battery the issue continues. I bought a refurbished alternator and it reads bad on the car but functioning on the advance auto machine. I decided to purchase a brand new alternator same issue with the battery light flashing off and on. I had my mechanic check the fuses, change a rusty connector to the battery, serptine belt and even changed the starter relay and same issue. I got the ground wires checked to make sure it was functioning correctly. I drove the car today with the radio and air conditioner off and the battery light did not flash because there was no load on it. My mechanic literally gave up and said to take it somewhere to see if there is an electrical issue. I don't know what else to do. Someone please help!