Car Stopped - Assortment of Codes

The P0A08 is the headline code here, all the others are on because of it.

P0A08 is set when all conditions below are detected:

• DC / DC converter internal circuit malfunction is detected
• DC / DC converter enters fail-safe mode
• Auxiliary battery voltage drops below 11 V

The areas that could be the problem are:

• The auxiliary (12 V) battery
• Fusible link block assembly
• Fuse (for 12 V electrical equipment)
• Engine room relay block
• Inverter cooling hose
• Water pump with the motor assembly (inverter cooling water pump)
• Cooling fan motor
• No. 2 cooling fan motor
• Wire harness or connector
• Inverter with converter assembly (DC/DC converter)

Following the inspection procedure in the repair manual will step you through the procedure to rule in or rule out each of those problem areas one-by-one. Hopefully, you find the problem is one of the less expensive parts before you get to the Inverter with converter assembly (DC/DC converter)

First check the 12 V battery is between 10 V and 13.2 V. If it is at the 10 V volt end of the range, charge it up and test that it is still serviceable. Replace if necessary. This is not the cause of your problem but could be damaged as a result of your problem. The 12 V supply needs to be good to effectively troubleshoot your car.

As the car failed while driving, the sixth item (I highlighted in blue) is highly suspect. This occurs when the inverter cooling water pump (ICWP) shorts out and opens the AM2 fuse. With the AM2 fuse open, the car dies. If you test the AM2 fuse (with an ohmmeter) and find it open (blown), i. e. has no continuity, replace the ICWP first and then replace the fuse. The car can be made drivable for temporary short (less than 40 MPH) drives by unplugging the ICWP and then replacing the 15 Amp AM2 fuse. The attached image shows a convenient place to disconnect the ICWP, the second image shows the ICWP, and the third image shows the location of the AM2 fuse.







Unlikely given the circumstances, failure of the second item (Fusible link block assembly) is usually linked to a botched jump-start procedure. Have you or anyone (even AAA) tried to jump-start your Mother's Prius?

 

Some good info here, but if the OP's mother "got the car started again" and drove it to a local shop, then it wasn't caused by the AM2 fuse going open.

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