isabellatiger8
SupraIV Overvoltage Issue
Summary of the thread
A 2023 Toyota SupraIV owner reported consistent overvoltage fault entries and intermittent system failures, suspecting a heavily discharged or defective battery. Another owner with similar issues suggested checking the alternator output, as it could be spiking and causing electrical problems. After following this advice, the initial owner confirmed that the alternator was indeed overcharging, leading to the issues, and had it repaired, resolving the problem.
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4 comment(s)
isabellatiger8 (community.author)
Thanks for the quick response. I haven't checked the alternator output specifically. How did you determine that was the problem? Did you notice anything else unusual before it completely failed?
christopherloewe69
Yeah, after replacing the battery, the problem came back a few days later. The car was stuttering while giving gas, which felt like misfires. Then, more electrical issues. I'd suggest getting it checked by a workshop; probably your car ECU or the circuit protection is broken.
isabellatiger8 (community.author)
Much appreciated! I took your advice and had it checked at a workshop. You were spot on; the alternator was indeed overcharging, leading to the issues. Ended up costing 290€ for the repair, but everything seems to be running smoothly now. Thanks again for your help!
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TOYOTA
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SUPRAIV
christopherloewe69
SupraIV owner here too. Sounds familiar. I had similar overvoltage errors and random system failures. Did you check the alternator output? Mine was spiking, frying everything.