U0100 culprit?

I bet the rodent chewed some wires. Check the fuel pump and wiring at the gas tank. I believe the pump runs on the EFI fuse.

 

Sorry about the post about the fuel pump… I didn’t see the post that you had fuel pressure.


Pin by pin test to test the resistance of each wire. However if you plugged the ECM into a known good car and the fuse blew it’s a good chance that you have a bad ECM and that’s it. I have ran into the same UO100 code and the diagnostic chart said to start with a “known good ECM”. I put one in and it fixed the no start and codes. ( this was on a Honda CRV)

 

When you have a short (blowing a fuse) it’s a hardware problem not a software problem. Reprogramming is for the software.

 

The Gen2 prius ECM is plug and play. I got a used ECM on ebay for $25- I just matched up the numbers on the case. Plugged it in and it worked. Stuff like the VIN, immobilizer/ security/ SKS isn't stored in ECM. About the only thing I would do is clean the throttle body so the ICE can start and idle normally (ECM loses idle and fuel trim adaptives when it has no power).

I think any Gen2 ECM should work, but there might be some (minor?) differences in ICE operational software depending on ECM part number and revision level. Don't know if that really matters or not.

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The culprit that was causing my EFI fuse to blow was exposed 02 sensor wires that were rubbing against the body. The 02 sensor im referring to is the one you access by going under the passengers side of the vehicle. Sorry, im not exactly sure what that particular 02 sensor is called. Only know it caused my 15 EFI Fuse to blow.