Prius don't start

The 12V battery was just replaced.
itndave: are you suggesting load testing the HV batt? If so I'm not sure where to find a load capable of that kind of power except the car itself.

 

You don't ever load test the HV batteries, well at least never mentioned in the forum, usually its all about load testing the 12v battery.

 

I've got a similar problem with a brand new Prius 3, 2010 in Moscow (Russia, yes). It doesn't sell at all here, just a few units a month.. The dash all lights up, but the only symbol that is not lit is the one that used to say "READY". The battery is new - xenon is shining, but there's no "READY". After several attempts, it starts. It's not yet cold, just a bit above 0 Celcius. But the problem appeared right when it became colder. After it had gone in temperature, the problem dissapeared. Now it's again. So, if it's with the brakes? The problem persists in a newer generation of Prius, that' sad. The dealer hadn't identify it, I took it out yesterday, and it doesn't start again.

 

Maybe the brake light switch needs to be adjusted? Press very hard on the brake pedal, as you are trying to start the car.

 

My '05 just started doing this - everything lights up but no 'Ready' and no start. Have to do a hard power down. A week or so ago, I started getting the red triangle showing up in the morning for the first start when we had a couple of colder days. Then everything was fine. But today it was cold again (about 37 F) and it wouldn't start at all. Tried a couple of times. I sat a few minutes thinking and then tried again and it started up. Started up fine the rest of the day. A couple of times I had noticed a funny noise from under the hood kind of behind the glove box but thought maybe there was a leaf stuck. I don't know. My son is checking the battery now. I only have 66 k miles on it but 6 years seems like a pretty long time to have the original battery so I'm hopeful that is the problem. Thanksgiving weekend isn't the best timing for getting it looked at, though.

 

The best bet is to connect a scantool and see what codes are set. The car will usually tell you why it's not going ready if there is a fault. The most common reason is a marginal 12V battery. When temperatures are low, the voltage drops in this battery when it's old and the car will fail to go ready. The problem is because this battery is only used to enable the computers, and not actually crank the car, (the larger hybrid traction battery actually does the starting) most people don't get a warning like "slow cranking" in a normal car and don't realize the battery is going.

If your battery is more than 4-5 years old, that is likely the problem. I recommend you order a superior replacement battery from This Place for $175 including shipping. It comes with all parts and instructions, and anyone with a 10mm socket wrench can do the swap in minutes.

If you don't think it's your battery, and are in the bay area and want to pay me a minimal amount for my time, I'll be happy to come diagnose your problem with the official TechStream scantool (same thing the dealer uses).