Nrew altenator overcharging new battery like the one that was replaced.

Tiny
CMB31JEX9
  • MEMBER
  • 2004 TOYOTA TACOMA
  • 2.7L
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 47,500 MILES
Just put new belts and new altenator in 2004 toyota tacoma 2.7L 4 WD. The old altenator was 21 yrs old just replaced with new one. Does same thing. Overcharges.
Wednesday, October 1st, 2025 AT 2:45 PM

4 Replies

Tiny
BLACKOP555
  • MECHANIC
  • 10,386 POSTS
Overcharged by how much. And what brand alternator?
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Wednesday, October 1st, 2025 AT 7:12 PM
Tiny
CMB31JEX9
  • MEMBER
  • 3 POSTS
It was reading on multimeter over 17 volts while running. Its a brand new battery. So I disconnected battery from system since the old altenator destroyed the old battery. I am thinking of replacing just the internal voltage regulator with a new one.
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Wednesday, October 1st, 2025 AT 8:39 PM
Tiny
CMB31JEX9
  • MEMBER
  • 3 POSTS
Chinese aftermarket altenator.
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Wednesday, October 1st, 2025 AT 8:41 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Yep, I would get a Denso unit, also, make sure the battery cable ends are in good shape, the repair ends can be corroded and cause issues. Here is a guide to help test the new alternator.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Please go over this guide and get back to us.
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Tuesday, October 7th, 2025 AT 10:44 AM

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