I just replaced my alternator, and installed an external voltage regulator, to bypass the computer controlled regulator, and my battery still won't charge. What could be wrong, now? This is on a '99 Plymouth Neon. I have checked the output of new alternator and all cable connections. Voltage output at battery dropped from 12.56 volts, to 11.95 volts, when engine was cranked.

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right on BILLBEAN !!!
But I still think the alternator can be connected to the battery directly with the proper amperage regulator...
I did that on my self built boat and that worked now if the battery is charging , then nevermind the ECU... Unless there is a possibility that you might burn the main cpu...
Unlikey but not impossible if there is an jndetected prblem or short...
GOOD LUCK BUDDY !!!
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