Alternator and battery new

JEPSI79

MEMBER
2003 TOYOTA SIENNA
AUTOMATIC
300,000 MILES

Had my battery and alternator replaced a few months ago. Last week the battery drained flat got it replaced. A day later the battery was drained again. Took my alternator out and took to Advance auto parts and Auto zone to get tested and both places said the alternator is good. Any insight would be greatly appreciated. Thanks and God bless.

3 Replies

STEVE W.

MECHANIC
13,446 POSTS

Testing out of the vehicle is a start, but you need to test the actual charging system in the vehicle. It sounds like you have a very large power draw and that will not show up without on vehicle testing of charging output, battery load testing and parasitic drain testing. It could be something as simple as a bad wire connection or as bad as a module that is not shutting off.

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Thursday, May 18th, 2017 AT 8:13 AM

JEPSI79

MEMBER
2 POSTS

A bad wire connection to the alternator or battery? I was also told something about fuses as well.

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Thursday, May 18th, 2017 AT 8:19 AM

STEVE W.

MECHANIC
13,446 POSTS

Bad connection could be anywhere, bad alternator connection to the battery would make the battery supply all power as the engine runs, until it shuts down because the battery dropped out. Bad connection from alternator to PCM could mean the alternator does not charge because it is not being controlled.

The fuse would be Alternator S fuse, five amp and located in the fuse box under the hood on the drivers side. You could also check the ignition fuse but If the engine ran this one probably is not an issue.

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Thursday, May 18th, 2017 AT 3:00 PM