hybrid system malfunction on a 2016 Prius with 115k miles.

The Prius 12V battery is not used to crank the motor, only to power on some electronics, thus a large 12V source is not needed to "jump start" a Prius. A large 12V surge could fry some delicate electronics, and in fact might be the OPs problem with EEPROM codes.

 

IMO sometimes you don't want to speculate ahead as to what something "might" be.
In this case?
"Hybrid System Failure. See your Dealer" would of been my starting and stopping point.
Especially with a vehicle that is still under warranty.

The danger is jumping batteries that may not need jumping, or disassembly of parts that don't need disassembling.
I know we all hate dealership service centers. BUT...sometimes in avoidance of visiting one...you can end up having to spend much more money to resolve the problem.

 

Agreed, a dealer may initially cost more than your local independant garage but they have the Toyota trained technicians that usually have more knowledge of the Prius and it could end up costing less in the end.

 

No, that isn't how electricity works. 12V is 12V. Whether the source is capable of supplying 1A or 1000A doesn't matter if the load is only going to draw 100 mA, then that's all it's going to get.

 

What about the differential in voltage between the two cars, one with a full battery and a powerful alternator, the other with a flat battery and delicate electronics ?

 

For about 20 years, I've declined to help people with a "jump start" after a work acquaintance helped someone out, and it blew his computer costing nearly $1000.