Check Engine Light and Triangle; Car is acting weird

to get some understanding of rebuilding the hybrid battery, see the thread in the gen 2 prius technical discussion forum titled 'gen II prius Individual Battery Module Replacement' by member @ryousideways

 

it's possible. certainly worth getting the info from them to see what it is.

 

If stuff is on, it definitely shows a discharged battery, but isn't incredibly low. Remember, C2318 is logged by the transmission control ECU, likely while it is trying to park or unpark, and the timing of that can happen to be when other electrical loads are active too; it probably indicates the battery has an open-circuit voltage somewhat above 9 (about 10½ is considered completely discharged for a typical 12 volt), just being pulled down to 9 by the load.

This is a possibility that gets more press than it probably deserves. Don't forget that the actual logic circuits in the car's ECUs probably operate at 5 or even 3.3 volts; there's a lot of headroom even when the 12 volt battery is awfully low. Just by simple accidents like leaving lights on, I've seen mine pulled down to 7 volts during (unsuccessful!) starting attempts, and I've done this more times than I'd like to admit, but I've never seen the ECUs give me 'false' codes or dash lights as a result. They may give me completely accurate codes telling me just what stupid thing I did, and we saw that here too, where even at 9 volts, the ECU simply recorded, in a functioning and businesslike manner, that it had seen 9 volts, and exactly what was happening when it did.

In your case, you are the proud owner of one trouble code pointing to each one, but probably neither one was caused by the other.

-Chap

Edit: I should add that I've also, quite uneventfully, recharged the 12 volt several times after such discharges that it reached 8 or 7 volts under starting load. Strictly speaking, yes, its expected life probably did become a hair shorter each time ... but to me, just having seen your battery hit 9 under load would not make me automatically give up on charging it.

 

right. but if it isn't on, it's incredibly low. as for the glitchy computers, i can only refer you to the old 'stuff acting weird?' thread.

 

The first time my hybrid pack took a dump was when I hit 114K miles. If you have the time you can rebuild it yourself. The second time my hybrid pack needed to be rebuilt my brake actuator assembly failed around the same time.