I have a 2003 ford focus wagon, automatic transmission, 140,000 miles. The battery light has been going on and off for 5 months, and the car has shut down several times. I’ve had the following replaced/repaired:
Spark plugs replaced. Two days later, car died.
Battery replaced. Two days later car died.
Alternator replaced. 4 days later car died on a vacation trip. Before it died, the battery light came on when I had to accelerate, and also when going down hills. Frequency increased and power shut off several times. If I waited 10-15 minutes, it would start up again. Finally would not start up - completely dead. Computer diagnostics first said the alternator was bad. Then, while still hooked up to computer, the bad alternator indicator disappeared and the alternator reported no problems. Technician ran the car for a few hours every day for a week and took it for test drives but light never came on.
When I got back from vacation, the new alternator was replaced with a ford alternator - the theory was that some 2003 ford focus computer chips have trouble recognizing alternators that aren’t ford’s.
All was good for about 4 months. Then battery light started going on and off again - sometimes 20-30 times in 40 minutes, sometimes only 5-6 times in that time span. Computer diagnostics found nothing - light never came on.
Car was vibrating. Had engine mounts replaced 4 days ago, hoping the electrical problem was caused by something vibrating against something else that connected to the alternator, and if the vibrations stopped, the battery light would stay off. First 35 miles - no battery light! Then it started coming on again, but not as much as before the engine mounts were replaced.
Battery light seems to only come on now 1) Every time I start up and begin driving and I think the car shifts to higher gears; 2) whenever I go up hills - it has also come on a couple of times when going down a hill (just like before, when the alternator was replaced); 3) when I accelerate beyond 55 mpg.
I can get the light to go off if 1) I floor the gas pedal; 2) I pump the brakes; 3) I put the car in park.
Mechanics are stumped. I love my car, but every time I drive it now, I worry the entire time about the battery light and about the power shutting off. I’m ready to give up.