1.0 INTRODUCTION
Last time, we did talked about FAILURE OF INVERTER ASSEMBLIES, AND THE RISKS ACCOMPANYING SUCH A FAILURE.

Today, our focus would be on INVERTER/CONVERTER ASSEMBLY PUMPS.

So, let's get started in earnest.

Just in case, you missed out on the last episode, here's the link:

https://www.nairaland.com/4136773/toyota-hybrid-vehicle-maintenance

1.1 WHATS THAT PUMP, AND WHATS ITS DYNAMICS

An inverter/converter assembly pump, is a small electrically powered device, that works in tandem with the inverter assembly system. Its hot its plastic impellers enclosed in a black, small plastic housing. It would behoove you to note that this pump, isn't mechanically run, just like your conventional car, or like the belt driven pumps you've got in the first generation Prius(2001) cars, or on some 2005-2008, Prius.

The inverter pump, is powered by your car's auxiliary battery (12volt, maybe 35Ahr). These batteries are quite different from what you've got stocked in a conventional car.

The pump basically functions as a normal standard pump. Here, I meant just like the pump characteristics in your homes' submersible pumps, or a conventional mechanically driven car pump, it pumps Toyota's long life coolants through the inverter systems network of electronic components embedded in the inverter.

Inverters operate under very extreme temperatures, when they're performing their functions: inverts the DC voltage output from the hybrid battery, in such a way that the requirements of all the hybrid systems, such as the transmission, AC system, and the electric motors, MG1 and MG2, are operating at acceptable thresholds.

These pumps, have got stators, with copper windings, on them.

If you want to have a feel of how hot the system is, lest take for instance, your electronic gadgets, such as laptops, phones, and even your TV sets, are always very hot, as constant voltages and currents, try to feed all the electronic components embedded on the PCBS (power circuit boards). These devices, are sometimes, air cooled, and in the case of the inverter assembly system, it is water(coolant) cooled.

The circulation of the coolants through the inverter cooling system circuitry, also cools the transmission system of the car. They're in fact, all looped(linked) together.

But note that you've the transmission system fluid (Toyota's WS), totally secluded from the inverter coolant compartment, so they don't stand the chance if mixing up.

1.3 WHAT ACTUALLY KILLS THAT PUMP?
You might have experienced a gradual, or sudden pump (whether a submersible in-house one, or in tour conventional car), suddenly fails, or begins to fail.

The following, are some of the causes of failures on all pumps, including the inverter pump.

¶Age.
An aging inverter assembly pump would definitely have it's revolution(RPM) reduced to let's say, up to 1/2, its assigned speed of revolution. Let's assumed the standard RPM for a known good pump is 3284rpm, and over the years, with it's usage, the rate of revolution would definitely be halved, or even fail.

The plastic impellers on the pumps would suddenly fail, and not even deliver the volume and pressure of fluid required to cool the inverter, and the transmission system.

¶Expired inverter assembly coolants.
Lits of folks, usually assumed fluids, not just the transmission fluids, radiator coolant, but also the inverter assembly coolants, do not expire.

Coolants are meat to have a higher boiling points, than water. Water, sure, has a good thermal characteristics, that would be compromised, when the operating temperature of a water cooled system, exceeds a certain T°C(more than 100°C), water's thermal characteristics, gets compromised.

It is at this stage, that coolants, because of the presence of additives, such, ethyl glycol, with the addition of other proprietary additives, are used to suppress the "voltage spikes" (I mean, excess temperature, rather), in such a system.

As time goes on, say, a maximum of 2/3years, the additives in coolants breakdown, and firm what we calk, sludge, etc, which are the prime suspects in the clogging and corrosion radiators/inverter assembly

¶Electrical malfunctions. Since the pump is powered by the 12volts battery, when there are issues such as open/short circuits in the circuitry if the battery power feed to the inverter pump, the pump gradually, or instantly KAPUTS, and ceases to function.

From our experiences, we've noticed pumps fail, due to shorting of the internal windings.

¶Production plant mistakes. I know some people might not agree with me on this, but it sure happens that, despite the AI(artificial intelligence) blablabla employed in some production facilities, human errors are still bound to happen. If don't agree to this, what would you say, could be the cause of the recent reported cases if the Samsung battery fires? Would you say, it didn't happen, or what? Ask your friend, Google, you've have thousands of studies on production failure of products newly launched all over the world.

With this, it shouldn't surprise you that a 14year old Prius/Highlander/Camry/Nissan leaf, etc, would definitely have its inverter pump fail, some day, because of a known defect.

For instance, in the Prius, 2005, or so, we've got lots of issues with inverter pump failures. The real cause of such failures, gas being reported by Toyota, to be a sudden shorting of the windings on the stator. That caused the pumps to short, and stop working.

Such pumps, have being upgraded to something better.

1.4 SIGNS A FAILING OR FAILED INVERTER PUMP

¶Overheating surfaces. As you drive a few kilometers, you'd realize the temperature icon(thermometer) pop up the MFD(multifunction display).

In such a situation as this, the best bet for you, is to stop the car, if you were driving, and allow it to cool down, before continuing the journey. I mean, seeking for diagnostic help.

¶Inverter damage. You'd suddenly notice the operations of the car's hybrid system, perform erratically.

The inverter system, because of it's quest to protect itself, and the hybrid system, would shut off the system, through the AM2 fuse on the bonnet area.

When you persistently use the car with a inverter pump failure, you stand the risk of destroying the car.

The inverter assembly, is like the car's processor. It processes billions of bites of information per seconds.

1.5 CHECKING IF YOUR INVERTER PUMP IS WORKING.

As an owner, or potential owner of a hybrid vehicle, you should be able to carry out the following simple test on your inverter system. This simple test, would enable you know if the car's inverter pump, is functional, or not.

¶Open the inverter coolant reservoir tank cover

¶Go and READY the car

¶Observe for some kind of turbulence or movement of the coolant.

Results:
∆If the coolant is moving, the pump us working OK.
But remember, this pump turbulence isn't a perfect conclusion. You've got to look at the RPM of the pump, and compare it to a standard.

∆If there is no turbulence, it means the pump has failed (shorted out, or open circuited).

1.5 HOW TO REPLACE THE PUMP.

Disclaimer:
I am not responsible for any damage or injury that you might incur, by not performing the replacement, following Toyota's recommended procedure(s).

If you're not comfortable working around high voltage system, please, do not attempt to performed this service. It's better you pay some few bucks to a friend, or take the car to a dealership, to have it replaced.

This is HOW!
¶get the service plug removed, including the 12volts battery

¶remove the inverter coolant hose plumbings, and trap the existing inverter coolants. You could actually use it later, after replacement of the pump.

¶Access the 10mm bolts on the pump, and loosened them.
Its usually sometimes difficult to access the pump, because if the inverter.

Here's a trick: Remove the front and side 12mm/14mm bolts holding the inverter assembly down, and then lift the inverter gradually upward. That would give you more space to remove the pump.

¶After replacing pump, ensure the inverter system is bled of pockets of air bubbles trapped in the system. This would go along way in ensuring the pump operates at a high efficiency.

The bleeding procedures on this pump, is quite tricky.

You can use your Toyota scan tool to command the system(pump), or so the bleeding, alternatively. That, I can't disclose here.

NB: Bleeding the system only occurs after the inverter coolant has being introduced into the inverter assembly coolant reservoir.


1.6 CONCLUSION
Nothing in this "sweet world $, would last forever; and so its the various components in your car. But it would be if immense help, to have an idea about how these systems, and components operates, and what to look out for, and implement, in such a system, before they eventually fail.





PS:I intend to update this thread, as time goes on.




Regards,
Igono Joseph Okeme
DW Nig Ltd
08066643532
Info @dxta.net.ng/oigonojoseph@yahoo.com
Lagos, Nigeria.

I am enlightened, i will contact you soon. Am expecting a camry hybrid car soon. thanks for knowledge sharing.

@moskylatata: Appreciate your comments Sir!
Expecting to hear from you soonest.