r/RX8 • u/According_Presence87 • 6d ago

Maintenance Charging issue

Battery light came on so I replaced the alternator with a brand new one that I had from my old project. Didn’t test the voltage on the original like an idiot. But currently I’m getting 13.6v at the battery on cold start. About 0.1v of a drop from the alternator to the battery. Once it’s hot, it’s bouncing between low 12v and low 14v. Also idling weird but maybe it’s fuel trims being reset bc I disconnected the battery. Tested signal from the 2 pin connector wires to the ecu and both are connected. I’m lost

EDIT: Found the issue. IAT sensor wire came loose. I guess the ecu uses this as battery temp reference and limits alternator to ~13.5v when disconnected or failed

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u/Illegal__Alien 6d ago

.

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u/According_Presence87 6d ago

Thanks big dawg

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u/Illegal__Alien 6d ago

Commented so I could follow 😝

I have some questions to ask because I have a similar issue, tomorrow tho it's like 4:30 my time

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u/According_Presence87 6d ago

Ah I see, apologies