SupraIV Overvoltage Issue

I'm getting consistent overvoltage fault memory entries on my 2023 Toyota SupraIV gasoline model with 130958 km. Systems are failing intermittently, and the battery is weak. Could this be a heavily discharged or defective battery?

4 comment(s)

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.

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?

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.

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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