What's Dr. Prius doing with read/clear "battery" errors, exactly?

Hi @jacktheripper,

Here's a post where somebody is using Dr. Prius, and taps the READ BATTERY ERROR(S) button, and gets shown the text "HV battery ECU error code: P0A93".



That's kind of not quite right, as P0A93 isn't a code from the battery ECU, and it isn't a code about the battery.

The ECU that reports P0A93 is the HV control ECU, in the dash behind the glove box, and the P0A93 code is about the cooling system of the inverter electronics under the hood, so having "battery" in the text is a bit misleading.

I'm sure Dr. Prius also does read codes from the battery ECU (inside the battery case), because that's where important battery codes like P0A80, etc., come from.

So, it would be good to know what exactly Dr. Prius is doing with the READ BATTERY ERROR(S) button. Is it sending two explicitly-addressed DTC queries, one to the HV control ECU and one to the battery ECU, and combining the codes? Or is it sending one broadcast DTC query and displaying whatever codes come back, but calling them all "HV battery ECU error code"s?

Maybe there could be a way to improve the UI so it is more clear what's going on, and codes would not all be called battery ECU codes even if they come from the other ECU and aren't battery-related.

Offhand, this makes me wonder about the READ ENGINE ERROR(S) button too. Does it send a specific addressed DTC query only to the ECM? Or does it send a generic query that other ECUs could reply to? Would Dr. Prius ever show a code from, say, the brakes, the steering, etc? Is there a different button somewhere for that?

I'm not sure yet just what suggestion I would make, if any; at this point I'm just trying to better understand what the app does now.

 

The OP in that thread I linked ended up happy when changing the pump for the inverter solved the problem and "the guy who did the work had a more sophisticated code reader than I have and he said my hybrid battery was fine!".

Happy ending, but you can see how it could be sad if somebody leapt into spending money on a battery because of the way the app displays a non-battery-related code.