2002 Tahoe Battery Light and Low Voltage

Discussion in 'Technical Discussions' started by rparikian, May 9, 2017.

  1. rparikian

    rparikian New Member

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    Feb 20, 2013
    Good morning everyone.

    Hope all is well. Have a strange issue with my 2002 Tahoe Z71.

    Battery light blinks intermittently. When it does the voltage meter in the IC shows battery voltage, approx 12V. After some period of time, minutes or hours, it will kick back in and voltage will be fine and battery will charge. More recently i am notcing the voltage meter spike up to 16+ volts for a few seconds then go back to 14 volts and then drop to 12 volts. Battery light still blinking.

    Drove it like that for a day and noticed it was draining battery, so i figured it was the alternator. Read up on this and most posts say its the alternator. Had it replaced with a rebuilt one. Couple weeks later same issue. Took it back to shop, thinking it was a defective rebuilt one, installed another one, this time problem didn't go away at all. They did a lot of troubleshooting everywhere and couldn't find a concrete answer. They kept saying its probably an issue with the 0GA cable i used in the Big 3 upgrade 3 years ago. Recommended i remove that and replace with factory cables but i don't have them anymore. insisted it had something to do with my aftermarket stereo system thats been there for 10 years.
    i had them remove the fuse to the sound system and problem was still there. They tested some more then said they found an issue with the wire harness that plugs into the alternator. Replaced it and all was good for another few weeks. Then two weeks ago, same issue. Took it back to the shop nad they cant figure out whats wrong.

    Things i have tested.

    Took the battery to auto-zone and they said it was bad even though its putting out 12 volts, but it was over 5 years old. Replaced the batter and still same issue. I disconnect the alternator while the car is running and i get 15+ volts at the alternator but once reconnected, it drops to 12. I have tested for voltage drop across the alternator and battery terminal. I read about an incompatibility with some aftermarket alternators and the internal voltage regulators.

    Any and all help will be greatly appreciated.
  2. Geno300

    Geno300 New Member

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    Oct 26, 2019
    My neighbors 03 is doing the same thing. What did you find out?