"Check hybrid system" failure & P0A0F code

prior to getting the check hybrid warning, was it running fine?

 

have you tested the 12v under load?

 

If all you need is the charger portion, I'm sure they're available at from prolong

Prolong Battery Systems. Extending the life of your hybrid. — Hybrid Automotive

 

When you checked the inverter coolant reservoir (to verify pump function), what was the status of the car, was it freshly started, or it had been driven for a while? If the latter, was the engine shut down or running? Would the inverter pump turn on if the engine was off?

 

With prolong I think you need to open the pack and install a harness?

Check the 12 volt battery voltage, if just to get it out of the way. Better, assess with something like Solar BA9 (electronic load tester, around $60).

 

Once the harness is installed, it is plug and play. But some up front install is required .

That equipment was something that helps keep the pack operating well for a long time .

We even made a believer out of @The Critic .

 

Toyota’s Repair Manual for the 2010 Prius is available by subscription to techinfo.toyota.com, as @bisco kindly mentioned, and from other sources, some of which may be available to you at no cost.

The Techstream software can check one system or ECU at a time, if you pick it from the System Selection Menu, or check all of them once, if you use the Health Check function. If you just checked one system, you’ll only see the diagnostic trouble codes (DTCs) from that system. There is also a CAN Bus Check function, which shows whether Techstream can communicate with each ECU, without trying to retrieve DTCs.

Techstream isn’t a guided fault-finding system like those provided by some other automakers. It’s just a tool for the technician to interact with the car’s computers, and it’s meant to be used together with the Repair Manual procedure for each DTC.

For DTC P0A0F, there should be more information available, however. The Repair Manual lists six INF (information) codes for this DTC, one or more of which should be shown in Techstream. INF codes 204 (abnormal engine output), 205 (engine is unable to start), 206 (engine component malfunction), 524 (NE signal error), and 525 (GI signal error) all mean that the power management control ECU received a malfunction signal from the engine control module (ECM), and the ECM should have stored one or more additional DTCs indicating the specific malfunction. Check in Techstream under Powertrain > Engine and ECT > Trouble Codes. INF code 238 (transaxle input malfunction) is different and has a longer procedure in the Repair Manual.

(NE and GI, by the way, are the crankshaft and camshaft position signals, respectively.)

 

Toyota seems to use “B+” to refer only to the auxiliary (12-volt) battery, but I assume you mean the hybrid vehicle (HV) battery, for which the voltage is not available in the engine compartment unless the car is in READY.

This is an important safety feature of the hybrid system. The HV battery is kept electrically isolated, by the system main relays (in the HV battery junction block assembly near the battery), until the power management control ECU sends the signal to close the relays, connecting the HV battery, via the frame wire, to the inverter with converter assembly in the engine compartment.

I can’t comment on the state of the HV battery, but I agree that it’s not a good idea to discharge it further.

Let me offer a possible alternative, however: if you just need Techstream to read the stored DTCs in the ECM, you should be able to do that with the car in Ignition ON mode, rather than in READY. With the brake pedal released, press and release the power switch once to get to ACCESSORY mode, and a second time to get to Ignition ON mode; see the Owner’s Manual (PDF), page 164. A third press returns to OFF.

Ignition ON mode is similar to key-on/engine-off on a conventional gasoline car, and on a Prius, it causes the IG2 and EFI-MAIN relays to be closed, providing power to the ECM. The system main relays for the HV battery remain open, however, so the HV battery won’t be charged or discharged.

This also means the DC-DC converter won’t be recharging the auxiliary (12-volt) battery, so you may wish to connect a 12-volt battery charger to chassis ground (–) and the jump starting terminal (+) under the hood, making sure to get the polarity correct. (See Owner’s Manual pages 543-544 for the location; ignore the rest of the jump starting procedure.)