12v Battery Question

Yes, he more than likely blew one to a few fuses. One that is not so easy to remove and replace is the Fusible Link Block Assembly (100A DC / DC-S)

TMR-JWAP says he has seen several reverse polarity jumps performed. Every reverse polarity jump has blown more than just the fusible link. You should check all the fuses in the under-hood fuse box.

You can use the search feature above to research it more.

 

Well, it certainly is a culprit. Just to reiterate:

 

... and also the little two-fuse block that attaches to the battery + post. If the little 5 amp fuse there blows, there will be a code for the DC/DC converter, and somebody might tell you the inverter got fried.

 

I always question myself for posting this, but when in a desperate situation, and the cause of the short circuit is known to have been repaired and fuses replaced, this temporary fix can get the car going again so you can get someplace safe.

2008 Prius won’t start | PriusChat

 

Nope, P1121 is likely mechanical with a check of the wiring and connectors involved with the coolant flow control valve thrown in for good measure.

There are plenty of posts here that you can find that will help you diagnose this fault by using the search function at the top right. Ignore any posts that talk about P1121 being a throttle position sensor fault. It could be that in other cars but not the Prius.

If you have a code scanner that says P1121 is a throttle position sensor fault go get another scan tool. Yours is not adequate. There is a thread pinned to the top of the Gen 2 Prius Technical Discussion forum that discusses some of the scan tool options and one that will work for the Gen 2 Prius.