2005 Toyota Prius won’t start, even after attempted jump starting.

I was having issues with an old 12V battery that would die on me, and jump started it 4-5 times. Bought a new battery back in March 2022 at O’Reilley’s and replaced it. Car hasn’t died since.

Went to go crank my car. It started and drove. Parked my car. Went back out to my car. Noticed a red triangle. Shut off my car. Tried starting my car again. Car wouldn’t crank.

Only the 1st sequence completed, where the dash lights came on. It wouldn’t go to the 2nd sequence, where the speedometer lights kick onto 0 mph. Tried plugging in OBD2 scanner and nothing popped up. Tried jump starting and charging it for 5+ minutes. It still wouldn’t get to the 2nd sequence . The car still has power and unlocks + locks, so I know the battery is not dead. Verified I had the jumper cables on correctly, and I have successfully jump started this thing 5+ times before, so I know how to start it. Unsure where to go from here.

• Also, I replaced the ABS module back in August 2021. Haven’t noticed any issues since and the new ABS unit sounds perfectly fine to me.

• Recently changed my front brake pads and front left caliper, back in March 2022. Unsure if any brake related issue, would prevent the Prius from starting or not.

• Hybrid battery only has around 80,000 miles on it, and was replaced a few years back (have the receipt to verify this from the shop it was done at). I still average around 45-50 mpg and have never seen a hybrid battery code kick on, so I doubt it is hybrid battery related.

 

Issue is fixed! I unplugged the 12v battery negative terminal, and let it sit for a few minutes. Put the negative terminal back on. It now cranks and drives fine.

 

Unsure for how long. It started fine and drove fine today too. No codes have popped up, even after starting the ICE engine. Yesterday, I checked several fuses, and the main fuse linkage block with an element, towards the front of the car. They were all good. Battery’s still good, and it read 12.5 volts on the battery, cables going to terminal, and also from the positive terminal, where you can jumpstart the Prius from the engine bay. I have a feeling it’s a battery relay related issue. But I could be wrong.

Going to drive around with a 10mm wrench just in case if this happens again. Will reset the battery again, if this issue occurs again.