Jim Grant's Tech Tips
'98 Ford Contour SE, Battery Light
Q: 8 months ago (35,000 miles) I had the alternator on my 98 Ford Contour SE replaced with a rebuild. Recently, (at 40k miles) the battery light started coming on immediately upon startup and stays on until I rev the engine. I replaced the original battery and the problem persists. I checked the battery voltage when the battery light is lit and the voltmeter reads 11.5V. After a quick rev to about 2,500 rpm, the light goes out and the voltage at battery terminals reads approx. 14.5V. Can you shed some light on what might be happening and why the problem appears to go away with a quick blip of the throttle? I would have thought that the light would come back on when the rpm's drop back to idle.
A: Replace that rebuilt alternator! The rebuilt you installed has a problem. If you let it go too long it will fail when you least need it to.