P3102 on 2008

Hey Folks.
I've scanned the forum for my code and have gathered it can be a bunch of things.
Here's what I've done recently changed fuel injector, had one sputtering. Changed plugs and coil packs.
Had the battery and alternator tested at parts store, both are good.

No other codes came back using Dr Prius.
Used multi meter to check the voltage, was low at 5 volts. Charged to 13 and drove next day for 50 miles (one stop with engine off for an hour) and on way home I got the infotainment warning to park on level ground and use parking brake. Charged again then went to parts store to check battery and alternator.
I saw in a post there are 7 sub codes w 3102.
Anything else I can check?
Any guidance on a good scanner thats not $500?