P0A78 and P0A94 + Help with Techstream

Greetings,

About 3 weeks ago my 2005 Prius gave the red triangle, check engine, and yellow exclamation point all at once right at startup. The ICE would not switch on and I ended up draining the battery while trying to drive. I switched the car off then on, and I was luckily able to drive the car home from work, although the warning lights remained on.

I ran a health check on Techstream when I got home and saved the results via my phone camera. I don't really know what I'm doing with Techstream save for running a simple health check, so I'm not sure if the images I'm providing will be adequate to diagnose the issue.

IMG_20191007_220838 by Rhunter posted Oct 31, 2019 at 6:08 PM

IMG_20191007_220852 by Rhunter posted Oct 31, 2019 at 6:08 PM

IMG_20191007_220916 by Rhunter posted Oct 31, 2019 at 6:08 PM

I cleared the codes and the warning lights remained off for about 3 weeks until this week when they came back on. During these 3 weeks the car behaved mostly normal, but it seemed that the electric motor was slow to switch on and off and was more jarring when it did so. It also seemed that the battery was charging and discharging more rapidly than usual and was being charged to full more often that I remember seeing before.

This evening right before I arrived home, the car really started to struggle. Per the info screen, the HV battery wasn't charging, nor was it providing any power to the drivetrain (neither the orange nor the green arrow was appearing). Also, the rear AC vent sounded like it was running full blast, and the car was severly lacking in power. The ICE was struggling to get up the hill regardless of how much I opened the throttle. The engine was revving, but wasn't delivering any power beyond a certain point. It was so severe that I was going 15mph and was worried if I would make it at all.

I'm not sure what to do next. I have the codes, but the info I've found online hasn't been definitive. It seems that these codes could be caused by a number of component failures. I just don't have the knowledge or experience with the electric drive system in this vehicle or the Techstream software to solve this on my own. Any help in diagnosing this will be greatly appreciated.

 

Those definitely help, thank you. Where could I get a copy of that service manual?

 

Ok, got the manual. I started following the steps on the diagnostic sheet for P0A94/588 and it seems that the terminals they're saying to test on the ECU end of the wiring harness don't actually have any wires, just open cells on the connector. I'm also not sure how to interpret the diagram for the Inverter side of the harness. It says "front" in the diagram, but I'm not sure which side is the front. Fortunately, the only possible outcomes from the diagnosis of this code are replace harness or replace converter inverter assembly. I'd like make sure the harness is ok before ordering a new converter inverter, but I'm lost on which terminals to actually test on the harness since the manual appears to be wrong. Any suggestions?

 

Update - I replaced the w/inverter converter assembly and the 12v battery, now I have 2 new codes: P3000-123 and the dreaded P0A80. I've already pulled the HV battery and am using my X4 to cycle the modules as I type this. I'll scoop up a handful of new(er) modules from eBay which should get me running again. The question is for how long. This will be the second time I've reconditioned the HV battery, and I'm already seeing reduced capacities relative to last time. I suppose it will last long enough to find another vehicle for which I can trade in this Prius. No Craigslist, I wouldn't feel right selling to a third party.