I just got this Prius, but it only starts when I jumpstart it. Once it’s running, the brakes are really stiff and there’s no power steering. The hybrid battery seems to be holding a charge, though. The previous owner mentioned they messed with the alarm system and put in a new one. Any idea what I should check next?
Sounds like your 12V battery might be bad. Try replacing it.
Tegan said:
Sounds like your 12V battery might be bad. Try replacing it.
The 12V battery has a 2023 date code, but I’ll still take it to get tested.
Tegan said:
Sounds like your 12V battery might be bad. Try replacing it.
The 12V battery has a 2023 date code, but I’ll still take it to get tested.
Batteries can go bad pretty quick sometimes, even within a couple of years. Try having it tested at an auto parts store or by AAA.
@Porter
Yep, I’ve killed two 12V batteries in my ‘02 Prius just by letting it sit for too long.
@Porter
You can trash a battery in a week if you really mistreat it.
@Porter
Motorcycle owners know this struggle… leave a 12V lead-acid battery discharged for too long, and it’s gone. I swear by trickle chargers.
Tegan said:
Sounds like your 12V battery might be bad. Try replacing it.
The 12V battery has a 2023 date code, but I’ll still take it to get tested.
Jumpstarting basically just gives it a fresh battery every time, so it’s likely the battery that’s causing the problem.
Honestly, just replace the 12V battery. If you think it’s still good, do a load test.
Vitt said:
Honestly, just replace the 12V battery. If you think it’s still good, do a load test.
The battery is from 2023, but I’ll get it charged and tested.
Edit: Does it have to be an AGM battery like the second gen?
@Flint
Yep, it’s AGM, but different from the second gen.
@Flint
My '06 Prius had a supposedly good battery that was only 1.5 years old, but it was completely dead. I went through three bad replacements from the shop before I finally got a working one. Even brand-new batteries can be garbage sometimes, just swap it out.
Dead 12V battery for sure. Replace it, even if it’s not that old. They can die fast if not taken care of.
@Flint
Could be a bunch of things causing the brake issue. Get a code reader, preferably a Bluetooth OBD scanner, and check for codes with your phone. That should help narrow it down.
Porter said:
@Flint
Could be a bunch of things causing the brake issue. Get a code reader, preferably a Bluetooth OBD scanner, and check for codes with your phone. That should help narrow it down.
I actually have one. I’ll pull the codes tomorrow.
Porter said:
@Flint
Could be a bunch of things causing the brake issue. Get a code reader, preferably a Bluetooth OBD scanner, and check for codes with your phone. That should help narrow it down.
Or just head to an auto parts store like AutoZone and ask them to scan it for you. They usually do it for free.
@EmilyToyotaLover
That works, but having your own code reader is really useful if you own a Prius, especially an older one.
Sounds like the brake booster might have failed and set off some kind of alarm, which could’ve led the previous owner to mess with the alarm system and make things worse.
Ridge said:
Sounds like the brake booster might have failed and set off some kind of alarm, which could’ve led the previous owner to mess with the alarm system and make things worse.
Would that explain why the battery doesn’t charge at all? I dropped the 12V battery off for testing and it was only at 3V. Makes sense why it won’t start or have any lights without a jump. Can it really just be a bad battery though?