[Prius](/topics-prius/) will not start

Thanks for using JustAnswer.com! My name is \*\*\*\*\* \*\*\*\*\* I'll try to answer your car questions. I'll start off with some basic checks to do, then we can get into more advanced diagnostics if needed. Let me know if any questions come up, or if there is anything I can do to help! You can update this message at anytime. - If you're not seeing the ready mode indicator coming on, or [engine](/topics-engine-toyota/) isn't starting, there could be issue with the high voltage system. We'll want to get it scanned for trouble codes, using a professional level scan tool, and see what might be setting. - Try using key in the backup slot if not done already and see if engine will start. If not, continue scan tool diagnosis. - List any codes that you're seeing, and from which module they were setting in, and I'll pull up the diag/repair information. - Lemme know if you have any questions while checking it out!

I diagnostic scan and no codes are coming upI'm getting the red car with exclamation pointWhere is the back up slot location

Will need to be sure youre scan tool can communicate with all of the modules, especially the high voltage controller. Recommend snap on/mac tools type scanner, if dealer level tool isnt available to be able to comm with all modules. Backup slot is the rectangle on the dash that key fits in, if it's a passive entry vehicle. List any codes you can get out of it, and we'll see what's going on!

Customer attachment 8/21/2020 8:06:14 PM

This is the scan tool I'm using and it's and it's all I have .. it checks the HV too

Those are pretty decent for pulling codes, and getting some engine data, but doesn't give us a full picture, or have direct communication with high voltage modules, Would recommend snap on/mac tools, or Autel scanner to look at the battery cells. The readings you're seeing are a bit misleading, should be 14 cells, usually about 7 volts each. Would recommend having mobile mechanic or locksmith come out and scan it, if we cant find a scan tool around the neighborhood/friends somewhere. Lemme know what you're seeing, or if any questions come up while checking it out!

Okay, I got it to crank by unplugging all the connectors from the auxiliary battery in the back

Did any codes set by doing that? Did ready light come on, and engine start normally now, or it just cranks over?

the car cranked up like normal but we just ran the codes and it keeps coming up with a error message I'm at AutoZoneI unplug ged all connectors to the jewelry battery again to restart it it wouldn't start when I got to AutoZone so the only way I can get it to restart is to unplug all those three connectors again

So, you're taking the high voltage controller offline, by disconnecting those connections at the battery, but able to start the car? Let's see about getting a proper scan tool on it at this point, and see what's going on with the high voltage controller. It may be going offline and causing issues with the other modules on the buss, or might need to be replaced, but will want to see the codes that are setting and run through some tests depending on what you're seeing.

Okay, thanks

You bet, you can update the message at anytime, lemme know what youre seeing, and I'll see what I can do to help! Thanks again for using JustAnswer.com!

Hi, it's Marc, from JustAnswer.com! Just checking in to see if you were still needing help with the vehicle, or if you were able to get it fixed up. Lemme know what ya found was causing the problem, that info might be able to help others out there if having similar issues. Thanks again for using JustAnswer.com, and please let me know if there's anything I can do to help in the future!

I had a friend of mine run the code and it was a few cells that were below 7.5 now can you have cells 7.5 That's good

Thanks for updating! If the computer was setting codes for the high voltage battery cells, they can either be replaced, or you can try to recharge them, but will need a special charger for doing this. You can also replace the whole battery if needed, there are quite a few options available for full replacement, if you decide to go that route. Lemme know if there's anything I can do to help, or if any questions come up while checking it out!