Battery light camry-what's causing it/?

have a battery -mostly while driving on the freeway but on also comes on at random times on street. It's a 95 toyota camry with 170k miles. Light comes on simultaneously with brake lamp light (icon is that of car with two rear lights radiating). The battery tested poor and I replaced -but the dash light behavior didn't change. Alternator tests as good while in car. I also run a wire from the +ve battery terminal to to the car cabin and monitor the voltage on my multimeter (grounded on cigarette lighter) while I drive -it's measures around about 13.5 V before starting engine then goes to ~14.55 V (very little fluctuation ~+/- 0.04 V) once the engine is started and idle, and goes up to ~14.70 V on the freeway (~14.67 when AC etc turned on). I look at the reading when the battery light comes on but it consistently measures ~14.7 V!



Aside: I took out the alternator for bench testing at Autozone before changing the battery -Autozone machine failed the alternator on all three aspects in test (including diode, etc) -but I question the reliability of the machine as it basically says my alternator is %26quot;dead%26quot; i.e. fails ALL tests yet it my car works on 14.7 volts! AND passes Autozone in car alternator test! (Was about to buy a new alternator from autozone from Autozone when I decided to let them test the new first on the same machine-but new alternator also %26quot;failed%26quot; the bench test-this makes me believe something is wrong with the bench testing!)



Anyway, I with figuring the lights: brand new 750 CCA battery, alternator producing spec voltage even while battery light on. If the it's the sensor problem or grounding how do I proceed? Could it still be a diode malfunction? What would the voltage be like a just one or more diodes in the rectifier malfunction? Help!Battery light camry-what's causing it/?If it's happening mostly while you are driving you may want to think about checking for a loose wire. It is possible and I've seen things like this happen that you hit a bump and your ground (ground wire) is effected. Check for a loose, burned, corroded wire.