I just purchased a 2005 Prius and it won't start, display shows the hybrid battery has 6 blue bars, lights on dash including red triangle. The car has 83000 miles with full Toyota service history, last service at 82000, though that was April 2016. The owner had taken ill and the car has done very few miles since, and has sat idle for quite a while. I have tried performing a few resets that i found on this site, but not having much luck, any help would be very much appreciated. Thanks, Alan
Question 1 is: Was the 12v battery dead? If it was, and you replaced it (or charged it), then the 6 bars is just the default value being displayed until the car can calibrate itself. It's very likely that after 2 years of sitting, you have an extremely weak HV battery, not a 6 bar battery. The HV battery is what provides the energy to spin the engine for starting. If the car never lost 12v, (like it was on a battery tender system) then the computers should still be good. The battery may have a ground fault due to electrolyte leakage. I've seen many modules get green fluid on them after sitting idle for a long time (typically on the negative terminal). This ground fault can be cleared by disconnecting the 12v battery for about 30 seconds and then reconnecting. It will allow starting the car one time (each time the battery is disconnected). You probably want to read any codes before disconnecting the battery. Get those codes and post them here. Then we can really get into providing help.
When a Prius sits for a long time the hybrid battery will corrode. Save yourself alot of head scratching and pull the hybrid battery out and check for corrosion. In the meantime you need a OBD code reader that has full toyota techstream software as theirs many hybrid battery parameters you need to look at. For a novice I recommend a VXDIAG powered by toyota techstream. $77 at Amazon.com. Plug and play on a laptop. It will report exactly why the car is unhappy. You have little hope to fix it unless you have the proper tools. Most likely code P0AA6 Iso fault.
What lights are lit on dash? As other member recommended check output on 12V batt. If hybrid battery fault light lit up, check the disconnect to ensure fully locked down (that one got me).
If those readings are accurate, then your HV battery is dead as a doornail. Each of those blocks should be 15v+ for a decent battery that's been sitting for several months. Hard to believe a battery could drain completely, but anything is possible after a few years of sitting. I don't know how much faith I have in those readings. You may want to pop the cover off and just check the voltage on the battery side of the relays. See if there's anything there. A good fresh battery will be around 216v. I've seen some batteries that have been idle a while come in around 175v. Only had a couple that were effectively 0, and they were original 2001-03 Gen 1's that were sitting for years.
I recently purchased a Prius with the same issue - sitting for 2 years. I disassembled the hybrid pack and found the orange connector on the battery control module severely corroded and eaten through the wires/pins on the voltage monitoring circuits. All cells read 0v and negative voltage when in reality half of them still had a charge, but with those wires being corroded, module interprets the open circuit as 0v. I ended up having to replace the pigtail and the battery control module.
I purchased a multimeter and tested at battery side of relays as advised, getting reading of 57.2 can the battery be saved or should I purchase a new one. Toyota have quoted £855 + VAT. I first tested with the service plug removed, when I inserted it I got 58.
turns out I have the same problem, I have ordered a new battery control module, but don't know how I'm going to fix the multi pin plug, 4 or 5 pins broke off and are jammed in. Do I need a whole new wiring harness?
I do believe that you can buy the new plug. There is a plugs section in the wiring manual. Keep searching here on PC Gen 2 forums (use the Advance Options). I seem to remember a post where someone replaced both the plug on the harness and the connector on the board. I also seem to remember that the board connector was not OEM. Take that all with a grain of salt, even I wouldn't trust my memory. .
