Got triangle and brake light on one day. Replaced 12v battery as it was original. Wife took vehicle and same lights come on and she looses power and braking. Had towed to dealer. Here is their diagnosis:" Code sets when voltage is below 11 volts. Test drove and lights are off and battery voltage is 13-14 volts. Called Toyota and started case. Case #150690704 and was advised to check individual cells in inverter. Customer will have to bring back when acting up." - I have several questions. I thought this was the big battery pack failure code. They make no mention of it. It might be cheaper for me to just install a used inverter, but Im not sure they are correct with this diagnosis and don't want to waste the money. Should I take back when acting up, put on a used inverter which might be the cheapest, or trade her off for a newer one? 2008 with 176k.
DTC P0A08 means that the DC/DC converter within the inverter is not working properly. First, make sure that the 12V battery cables are tight, especially the negative cable where it bolts to the body. Also check the dedicated jumpstart terminal in the main relay/fuse box next to the inverter. Tighten the bolt which secures a cable to that terminal, as that provides a connection to the positive terminal of the 12V battery. Bring along a voltmeter when driving the car. The next time the warning lights come on, immediately stop the car and put the gear selector in P. Leave the Prius READY and measure voltage across the 12V battery. If you find that it is much less than ~13.8V that is evidence the DC/DC converter is not working, at least at that moment. Also, purchase Mini VCI so that you can confirm for yourself the DTC logged by the car. Once you have decided that the inverter is the failed part, you can buy and install a used unit pretty cheaply. Good luck.
Hi Jaspernuts, I rebuild Prius batteries and live in Richfield, MN. Feel free to call or email with any questions about your car you may have. I have a Mini VCI cable and Toyota Techstream software so can do any diagnostics a dealer can. Code P0A80 is about the HV battery. Code P0A08 is about the DC/DC converter.
update: car has gone 300 miles without acting up. Resting voltage is 12.0 volts. Battery is a Toyota battery. I have never jump started it. Voltage was taken of the diag mode screen.
12.0 is well below spec. you may want to try charging it or replacing it. should be 12.5 or higher after the car has been off for a few hours. unfortunately, a lot of new batteries have been coming through poorly charged. the car won't bring it up to spec. the correct trickle charger will, if the battery is in good health. otherwise, it should be covered under warranty. a new battery should hold 13.0 volts.
