Prius v Display Audio Service Menu w Battery Check

I am suggesting that the original 2012 Prius v firmware did not operate that way. When the inverter’s power modules starting burning out, Toyota did a service campaign/recall to update the firmware to make the power igbts less prone to failure. Even then, many inverters have been changed under the extended “recalls”, but only after their failures stranded the owner. I had the firmware update followed a few months later by a failure.

 

Toyota just implied changes to improver reliability. It almost had to be software limits on maximum current and heat allowed through the inverter converter assy. They don’t release significant details of how their algorithms work.

One of the better sources is a collaboration with Weber State’s automotive department WeberAuto on youtube. In general Toyota is better than their competitors when it comes to safety related issues like sudden failures that could strand you on a freeway overpass or the like.

 

Useful Sequences

Realtime 12v Battery Voltage in Off or Running State
Check out your battery status/charging system by using the MFD Service Menu.

1 Press the Start button without the brake pedal.
2 Press and hold the "CAR" button on the MFD while turning the headlights on and off 4 times.
3 Press "Function Check / Setting" field on the screen.
-Function Check / Setting menu will appear.
4 Press "Vehicle Signal" .
-Vehicle Signal Check Mode" screen will appear, showing

Battery 12.2v ---------SPEED 0 Km/h
IG OFF ---------------TAIL OFF
PKB ON --------------ADIM/TCAN BRIGHT
REV OFF

The 12v battery voltage is shown and changes as load changes. Go to Ready and the 12v will rise.

Diagnosis Check MFD mode

A Press Start button without brake.
B Press and hold the "SETUP" button on the MFD while turning the headlights on and off 4 times.
C The red "Diagnosis Check USA" screen will appear.

Maintenance Mode to Continuously Idle Engine (Don't drive in this mode, damage may occur)
Useful for coolant change when adding new 50/50 antifreeze

1. Press Start button 2 times
2. Press Gas Pedal 2 times
3. Press brake and shift to Neutral
4. Press Gas Pedal 2 times
5. Press Brake and Press Park
6. Press Gas Pedal 2 times (hybrid warning light will start flashing)
7. Press Brake and Start button (starts engine, don't drive it, shutdown to return to normal)

(Don't drive in the above mode, damage may occur)

Invalid Mode for Brake Flush
Useful to brake flush without Techstream Scanner

1. Press Parking Brake
2. Press Start Button twice
3. Press Brake Pedal and shift into Neutral
4. Press Brake x8 in 5 secs
5. Press Park
6. Press Brake x8 in 5 secs and release
7. Press Brake pedal and shift to Neutral
8. Press Brake x8 in 5 secs
9. Press Park (Blinking brake light)
10. You are in Invalid Mode

Bleed rear brakes by holding pedal down
Bleed front brakes by pumping brakes
Power down to exit invalid mode

Consider using charger on 12v battery During process

 

The electrical system acts the same way as it does normally while the vehicle is stopped except the engine does not shutoff. So in "Maintenance Mode"" the battery may initially charge for a few minutes and then it will stop charging. But the engine will remain running instead of shutting off. The hv battery will discharge as normal and the system will start charging again when its low. Continuous idle is not forced charging but its useful for running the engine when replacing the antifreeze to ensure bubbles are removed. You can't drive in this mode as damage to the transaxle could occur.

Regarding "where does the excess energy go", the inverter determines the load on the MG1 motor/generator and can also turn it into the starter motor. So basically MG1 is not generating excess power although it may generate a small nominal amount. In this special maintenance mode, the engine is just rotating, except when the hv battery needs a little charge. You can actually hear the load of the engine change as the generator is enabled. Its similar to a normal vehicle's alternator, as amp demand increases actual engine hp load increases.

A basic look at a Prius transaxle may help.

Another decent video

 

The engine has one warmed up idle speed controlled by the computer. I think we are still trying to understand how the computers can control the Motor Generator's output. A component is the transaxle's variable speed planetary gear set, perhaps best explained in the above videos. Another includes multiple 32 bit computing modules receiving inputs and executing outputs in a high speed networked operation. In this area Toyota keeps most details proprietary but the links below from an electrical engineering company gives a flavor to an amazing achievement in electrical power control and miniaturization within a mass produced vehicle.

One link touches on computer controlled engines while the other explores computer controller electrical power systems as employed in hybrids.

https://www.eetimes.com/special-issue-inside-the-prius-part-4-controllers-keep-dual-motors-humming/

Special Issue: Inside the Toyota Prius: Part 5 – Inverter/converter is Prius’ power broker | EE Times

 

Permanent magnets and no brushes makes them small, reliable and expensive up front.

 

Basically if its low when you give it to them, plus if its on its last leg most likely.

 

There are now low cost heads up displays and similar that will display coolant temp, 12v voltage, speed and other things. Some around $30. They do run off the obd2 but do not require a scan tool.


This one has a small bug in that the coolant displays up to 199F. After 200 it displays the last two digits, eg 205F displays as 05F.