Need a little help

Pretty sure the P3020 is just telling you the HV battery problem is in Block 10, which is the 19th and 20th module from the non-ecu end of the battery. This is just what the ecu has picked up on most recently. There are likely other blocks with problems, like block 1.

The P0A09 is saying the DC-DC converter has a too high or too low input. The DC-DC converter gets it's input from the HV battery and converts it to a lower voltage to supply the 12v bus. Kind of like an electronic alternator. Could very well just be related to your HV battery problems.

 

It's important to check the details of the code though, because the 'input' the code is talking about is not the power 'input' the converter gets from the traction battery. The 'input' the code is talking about is the NODD signal, which the converter and the HV control ECU use to communicate with each other. It uses ordinary electronics-friendly voltages to convey things like "normal operation" (5 to 7 volts), "abnormal operation" (2 to 4), or "stop converting" (0.1 to 0.5).

So the code means a weird signal voltage on that NODD line; it doesn't mean a weird input voltage from the battery. The first thing the manual suggests checking is the wiring and connections on that signal line.

 

Here is one of two workups for P0A09 with subcobe 265 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8CPDF%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/21bpm/0a09265.pdf

Here is the other workup for P0A09 with subcode 591 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8CPDF%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/21bpm/0a09591.pdf

 

Oops, I missed that the subcode-591 version is talking about the VLO signal instead of NODD. Thanks.

Kind of off-topic, but looking at the diagram from the 265 workup, any electronics geeks with an opinion on why they decided to invert into a transformer and rectify, instead of using a direct buck configuration as they do in the boost converter for the powertrain? Maybe the larger voltage difference, and to give the output capacitor an easier life?



I think I've convinced myself the choice of a center-tapped secondary allowed them to have just one diode drop involved in the output at any one time.