If you have code P0A0D on a Toyota Prius (or another model Toyota/Lexus) there's likely a simple fix to get you back on the road again. Typically, if the vehicle has set this code the car will turn on but not go into gear. Sound familiar?
Here's a technical description of problem locations from a Toyota training manual: When the hybrid vehicle control ECU detects that a safety device is operated, it will prohibit hybrid system operation or shut off the system main relay. There are four safety devices in four different locations. The first safety device is located at the HV battery service plug grip. The second one is located at the connector cover of the inverter with converter assembly. The third one is located at the air conditioning harness assembly that is connected to the inverter with converter assembly. The fourth one is located at the inverter terminal cover where the motor and generator cables are connected to the inverter with converter assembly. If the service plug grip, inverter with converter assembly connector cover, inverter terminal cover, or air conditioning harness assembly is removed, the interlock signal line will be opened. If the vehicle is being driven, this condition will be determined to be an open circuit and the system main relays will not be shut off. If the safety devices are reinstalled correctly, the system will return to normal when the power switch is turned on.
Most likely cause — P0A0D from the hybrid battery
The P0A0D code is set when the high voltage interlock (big orange plug) is not properly installed or damaged. Generally this happens when someone has removed the plug from the hybrid battery and not correctly reinstalled it. Most folks forget the last step when reinstalling the plug. Don't forget, once you have correctly reinstalled the plug you must clear the codes/warning lights with a scan tool or by disconnecting the 12v battery. If you have performed these steps correctly and the vehicle still sets the P0A0D code, you may need a new interlock plug or there can be damage on the hybrid battery where the plug is seated.
P0A0D from hybrid inverter or AC
This code can also stem from a problem with the hybrid inverter or AC installation. If you've had to remove these components you'll want to go back and check the connections again. The Toyota description above references the locations of each safety connection.
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