How to change inverter coolant 4th gen

No, you don't need Techstream to run the pump. Just put it in READY after the initial filling.

 

Attached are the engine and inverter coolant change instructions. There's mention of Inspection Mode/Maintenance Mode, which I haven't tracked down as yet.

 

I noticed that Nutsaboutbolts drains the inverter coolant from the inverter itself whereas the instructions ML posted drains from the radiator. Am I right to assume they both have the same effect?

I would also note Nutsaboutbolts is working on a 3rd gen whereas ML posted instructions for 4th gen, but it was stated that the system is the same in both cars.

Thanks for the clarification!

 

Thank you so much for the files regarding coolant changes on a Gen 4 Prius. I found nothing online on how to do it. There are some changes from the Gen 3 that were confusing....but no more. Thanks again!

 

Does anyone k ow if you have to put the Prius in maintenance mode for the 4th Gen Prius coolant change? If so what is the instructions for doing so?

 

Second attachment in post 6 outlines the non-Techstream method. Seems like you just turn the car on and off several time, top up after each time, till it quits dropping.

 

What is Techstream? And thanks

 

Proprietary Toyota diagnostic/service software.

 

I have found that changing the inverter coolant to be exceptionally easy. There are no complicated passages like the radiator and engine coolant. It was easy on the Gen 3 and possibly as easy on the Gen 4.

No Techstream and no method specified by Toyota is actually necessary. Their technique is for the dealership or service shop that needs to complete the who operation in tive on the service bay in the most efficient manner as possible.

I used the UView method one time and found it not to be necessary.

Just drain the fluid, fill the reservoir, let it settle until no more immediate bubbling is seen, drive the car around the block and refill the reservoir to the full mark. During the next two weeks observe and refill.

That's all that's necessary.

 

@NutzAboutBolts video on 3rd gen inverter coolant change follows the Repair Manual, explains it well. A quick read of the repair manual procedure for 4th gen, looks to be the same.

 

I just got back to the dealer today and ask about the coolant drain and fill and found out their is also a COOLANT FLUSH that drain and flush out the old coolant that run through the engine? And I also found out that the inverter coolant and coolant fill tank are two different service. Do you really need a coolant flush or just a drain and fill?

 

A flush should only be necessary if someone added the wrong coolant or put in some kind of leak stopper stuff. A simple drain and fill is generally sufficient.

 

I'm confused about the gen 4 inverter coolant change. The car care nut has a youtube video where he shows the coolant being drained from the bottom of the transmission from a 10 mm plug being removed. But the above illustrations appear to show it being drained from a draincock plug on the radiator. He is a Toyota master tech and should know. Which is it?

 

The plug at the bottom of the Gen 4 transaxle is the transmission fluid drain. On the Gen 3, it is the inverter coolant drain.

On the Gen 4, the petcock is the inverter coolant drain.

 

Thank you.

 

Could be just language confusion: even pros will use the term “flush” to describe a simple drain and fill.

 

I came across this thread when researching how to do a coolant flush on the Gen 4 I just got. I've had a gen 2 and Gen 3, this is much easier then the gen 2, hopefully the bleeding will just work itself out. I didn't notice any air bleed instructions on the Gen 4.

I came here to add to this thread the instructions to get the car into maintenance mode without techstream which is mentioned multiple times in this thread. I'm sure it's also located elsewhere, but for simplicity's sake:

1 Engage parking brake if it's not on already
2 Press "Start" button twice
3 Press gas pedal to floor twice & release
4 Hold brake and go to neutral "N" & release
5 Press gas pedal to floor twice & release
6 Hold brake and press "Park" & release
7 Press gas pedal to floor twice & release
8 Coolant in inverter tank is now getting sucked in
9 Hold brake pedal down & push "Start" & release
10 Car should now be in "Maintenance Mode"

 

The repair manual (excerpt attached to post 9) doesn’t mention maintenance mode for inverter coolant change. It is required for engine coolant change though.

With inverter coolant change, it says to make the car “Ready”, shut it down, top up reservoir, till level quits dropping, is stable.

“Ready” is pushing start button while brake pedal is depressed, which will start the engine, after about 10~15 seconds. I’m not sure that’s helpful, necessary. With my gen 3 I did “On”, which entails two pushes of start button WITHOUT touching brake pedal. If you do Ready, limit to 5 seconds, then hit power button again (to shut everything off), would be my 2 cents, to avoid firing up engine. It’s still effective at dropping the coolant, in those few seconds.

 

OR on a gen4; just put the car into 'READY mode' - then hit the windshield defogger button. That should force the ICE to start. Crank up the heater to max; though I think that using the windshield defogger option should already force coolant into the heater core.

YMMV

 

I'd be hoping to avoid engine start.

This is inverter coolant change, right?