1.0 INTRODUCTION:
This thread, is focused on discussing common flash points prevalent in Toyota lineup of hybrid synergy drive systems, and proffer some solutions to them.

We'd discuss every aspect of the Toyota hybrid system, starting from the bonnet (engine side), down to the body, electrical/electronics, brakes, suspensions, etc.

It should be noted that this thread is not only limited to Toyota's brand of hybrid vehicles. but also, the hybrid lineups of Honda, Ford, Nissan, and others.

Hybrid vehicles, most especially the Toyota brands, are somewhat more complex than other auto car makers, simply because of the complexities involved in the hybrid system algorithms.

Amongst the hybrid system in Toyota's lineups of highlanders, and Lexus crossovers, its being observed, and also from our personal experiences, that the INVERTER/CONTROLLER ASSEMBLIES, and the BRAKE ACTUATOR ASSEMBLY have being known to fail, during electrical components performing above their set thresholds.

In this article, we're going to limit these problems, not only peculiar to the Highlanders/RX 400h, but also to Prius cars(but not prevalent), to inverter failures.

1.1 WHY DO INVERTER/CONVERTER ASSEMBLIES FAIL?
So, what does the inverter system does in these vehicles?

First and foremost, the inverter assembly, comprises of various ICs, electronic components, such as resistors, transistors, zener diodes, etc. It houses al of these components, in a rectangular like structure.

It's positioned at the driver side of the hood, when you open the hood(bonnet). It kind of looks like a conventional battery.

The inverter basically amplifies the DC voltage from the hybrid battery's nominal voltage of 384V, to something within the range of 600V.

This inverted voltage, is further fed to the three phase electric motors located in the eCVT transmission system, and to the electric AC compressor system. Some of this voltage is also converted and fed to the auxiliary battery through one of the motors, and through regenerative braking(I.e, when you are gradually coming to a stop, the kinetic energy fro. the wheels, are converted in to some form of energy, and fed back to the hybrid battery).

1.2 WHAT ARE THE COMMON PROBLEMS YOU MIGHT FACE WITH YOUR INVERTER?
I'm not trying to create panic in to your mind, but be less assured that, if you own a highlander 2006-2010; and RX 400h 2006-2008, and the vehicle has passed Toyota's warranty on replacement of vital hybrid system components (hybrid battery, inverter assembly, battery ecu, and hybrid ecu), which from my research, are warranted 100,000-150,000mi/10years, and the vehicle was imported into the country after that, you've got to understand that the cost of replacements of any of those parts would be borne by you alone. Not really encouraging, isn't it? Well, not really.

1. Coolant leaks at the interface of the inverter assembly.

SYMPTOM: You'd notice the pinkish colour of the inverter coolants spills at the edges of the inverter; and an overheated Inverter assembly, as a result of coolant leaks from the Inverter coolant reservoir.

SOLUTION: The whole inverter assembly has to be replaced, and would cost you, tens of thousands of naira(not dollars). This is for the price of a used one. Newer Toyota OEM are in the thousands of dollars. That could wreck your pockets.

2. Inverter assembly overheating. This, in some cases, the inverter isn't the culprit (ole) here, but the inverter water pump could/or have failed.

SYMPTOMS:
A thermometer symbol blinks, and finally shows on the MFD (for a Prius, etc); vehicle might not be able to move, and would finally come to a halt.

SOLUTION:
Replace the inverter water pump, and see if that solves the problem. Mind you, if its the inverter, there would be an inverter related trouble code(s) that would be logged in the ECU

3. Others.
In some cases, we've seen instances where a hybrid vehicle, suddenly just won't start.
If you're faced with such problems, try as much as possible, to isolate other Hybrud related components before concluding it is a failed inverter assembly.

SOLUTION:
Test hybrid battery nominal voltages, capacity, and the auxiliary battery (12volts), if there isn't power feeding the instrument panel for the READY light to come on.
After confirming all the above, replace the inverter assembly for good.


1.3 CONCLUSION
The inverter of your hybrid vehicle, is the processor, or CPU, that processes all that high voltage DC from the hybrid battery, amplifies, and distributes it to the various hybrid systems that requires them, according to demand.

They are very critical to the operations of a hybrid vehicle, and could fail at anything, in some cases, with warning signs as enumerated in the article.

The cost of replacement is almost near the price of a new Toyota hybrid battery, in the USA.


PS:
Don't use ordinary water, or non Toyota based coolants. Only use Toyota super long life coolants in the inverter. Reasons being that, Toyota's coolants, are specially blended to take care of the extreme heat generated in the inverter, that other coolants that aren't meant for hybrid vehicle applications.



Regards,
Igono Joseph Okeme
DW Nig Ltd
oigonojoseph@yahoo.com
info@dxta.net.ng
https://www.facebook.com/Dexterwise-DW-Nig-Ltd-767933589982123/
08066643532

Trygo weldone! You understand the hybrid system.

@Ricmayak1: Well, we're trying to do our best though.

Hi, ricmayak1: We're just trying our best.