The battery indicator is on, however

[logan_romerob]

The 3.3V6 alternator recently got a new one. While the engine is off, the battery voltage is 12.7. I acquired the car secondhand two years ago, thus the age of the battery is unknown. On idke, the engine voltage is 13.7 volts, and at highway speed, it rises to 14.2 volts. For some reason, clearing the computer by removing the negative cable from the battery didn't work. Excellent serpentine belt, idlers, and tensioner. The alternator died on me mid-trip, and the engine ultimately cut off, so I may use my OBDII code reader to remove any errors. Works perfectly when started.

[luna.wangnr]

No matter the RPM or anything else, I'll just pretend the light is on.

We still need to verify a few things:


The electronic control unit (ECU) may assume the system is undercharging if the battery sensor is faulty, which may cause the light to turn on. It is an integral part of the pricey negative cable's negative battery terminal. Unusual "soft" failures are common with them.

A defective battery chassis ground is limiting the battery's current. Make that the battery negative connection is getting electricity when connected to the hard chassis ground.

The battery can be dying despite your best efforts. One of these cars can have its battery light go out at any time, even while everything else is working.

[logan_romerob]

A few more items need checking, thank you.

[logan_romerob]

Once the new negative cable is installed, I will report the findings. Would the ECU simply assume the alternator is not under load and not need it to generate maximum voltage if I were to disconnect the sensor wire?

[imaninovakrz]

The AC ripple coming out of the alternator is another thing to look at; I know it's new, but... I've observed that it causes the battery light to remain on. The value shouldn't exceed 50 mVac.