My light comes on about 5 minutes into the morning drive, stays on until warmed up or the 15 mile drive the dosen't come on again rest of the day, no difference on power, Changed Battery couple of days ago, wireing harness a few years ago

I would want to monitor the charging voltage at the time that the MIL comes on.
Also would want to see if current recertification was allowing some A/C voltage into the system.

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