Brake, ABS, VSC, Bang

Unless you have noticed obvious clues of a dying 12V battery (like weak cabin lights for example) I doubt that is causing the warning lights that you noted. The presence of those lights means that the skid control ECU has logged DTC. The most likely reason is that the inverter is overheating which is causing the DC/DC converter to shut down, thus lowering voltage on the 12V bus. The skid control ECU is highly sensitive to low voltage since the braking system is electrically operated.

Check your inverter coolant pump to see if it is running, when the car is READY. Look for fluid turbulence in the inverter coolant reservoir, which would show that the pump is moving fluid.

I suggest you schedule a visit to your Toyota dealer at the earliest opportunity, to replace the pump if it is not working. If the pump is working, then you'll need to have the skid control ECU DTC read so that a diagnosis can be provided to you.

 

Did the SG show any stored codes?

 

Patrick,
Why do you think the SG did not pick up a DTC if inverter overheating is the problem ? I am under the impression that DTCs are the norm.

 

Because the ScanGauge (in an unmodified state) cannot retrieve DTC produced by most of the Prius ECUs. Prius has many more ECUs than most cars due to its hybrid powertrain. A generic device is going to ignore the DTC produced by most of the ECUs (such as the skid control, traction battery, transmission control, electric steering, air conditioning, and body. It might or might not read hybrid vehicle ECU DTC.)

 

ScanGauge will (should?) show P codes, including P0A93 for inverter cooling system malfunction (usually a pump failure). It will not show C codes (brakes). But, brake sensors are the pickiest about low voltage, so check that 12V first. Brake codes are "permanent" DTCs and will not be erased by removing 12V power.

 

There are four major DTC categories:

P - powertrain
C- chassis
B - body
U - network

P codes can be produced by the engine, hybrid vehicle, and traction battery ECUs at minimum. I wouldn't count on a generic device to be able to report all of those.

A simple test for someone who has a ScanGauge: when the car is IG-OFF, remove the orange traction battery interlock at the left side of the traction battery. Then try to make the Prius READY.

See what happens, and whether the SG reports any DTC. If it doesn't then you will know that it will not report traction battery and hybrid vehicle DTC.