The light first came on about a month ago, intermittently, every 3/4 days for about 2 weeks. Then it started staying on, alerting me 2/3 times in a 30 min trip. Then 30 mins into a hour drive home, every warning light flashed like it was Christmas on my dashboard. Got pulled over, cut off hoping it would reset, but the battery was dead. So, bought a refurbished alternator and a new battery. Installed both, but the light still stays on. Should I worry?

  • Welcome to Motor Vehicle Maintenance & Repair! Sep 18 '17 at 19:06

You need to check two things. First, check to see if the alternator is actually charging. You'll need a digital multimeter (DMM) to do this. Check it directly at the battery with the engine off, then once started. It should read in the neighborhood of 12.5-13.1vdc and 13.5-14.3vdc respectively. If the battery shows low with the engine off (say 12.0vdc or less), you need to completely charge it using a battery charger. If the battery shows good (before and/or after charging), but the alternator is showing low or if the battery continues to show a loss of power (numbers keep ticking down), take the alternator back to where you bought it and see about getting a different one, because the one you've got is bad.

  • 1
    @Jill Check the field and lamp circuits as well. either could cause a no charge situation and not set the MIL, but will set a code in the PCM.
    – Ben
    Sep 19 '17 at 21:39

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